diff --git a/.github/workflows/dotnet.yml b/.github/workflows/dotnet.yml
index b5307bab..4b5b04a7 100644
--- a/.github/workflows/dotnet.yml
+++ b/.github/workflows/dotnet.yml
@@ -79,11 +79,11 @@ jobs:
     - name: Pack TaggedUnion
       run: dotnet pack ./src/*/*/TaggedUnion.csproj --no-restore -o ~/nuget  -c Release
 
-    - name: Restore TaggedUnion.Tests
-      run: dotnet restore ./src/*/*/TaggedUnion.Tests.csproj
+    - name: Restore TaggedUnion.Tests.Old
+      run: dotnet restore ./src/*/*/TaggedUnion.Tests.Old.csproj
 
-    - name: Test TaggedUnion.Tests
-      run: dotnet test ./src/*/*/TaggedUnion.Tests.csproj --no-restore  -c Release
+    - name: Test TaggedUnion.Tests.Old
+      run: dotnet test ./src/*/*/TaggedUnion.Tests.Old.csproj --no-restore  -c Release
 
     # Result
 
diff --git a/src/core-taggeds-union/TaggedUnion.Tests.Old/GlobalUsings.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/GlobalUsings.cs
new file mode 100644
index 00000000..79c0d7cf
--- /dev/null
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/GlobalUsings.cs
@@ -0,0 +1,2 @@
+global using NUnit.Framework;
+global using NUnit.Framework.Legacy;
\ No newline at end of file
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs
similarity index 85%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs
index 581cc5b7..1b543c3e 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitialize.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void OrInitialize_OtherFactoryIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.Throws<ArgumentNullException>(() => _ = TaggedUnionExtensions.OrInitialize(source, null!));
-        Assert.AreEqual("otherFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactory", ex!.ParamName);
     }
 
     [Test]
@@ -23,7 +22,7 @@ public void OrInitialize_SourceIsFirst_ExpectSource()
         var other = TaggedUnion<object, StructType>.Second(SomeTextStructType);
 
         var actual = TaggedUnionExtensions.OrInitialize(source, () => other);
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void OrInitialize_SourceIsSecond_ExpectSource()
         var other = TaggedUnion<object, RefType>.Second(PlusFifteenIdRefType);
 
         var actual = TaggedUnionExtensions.OrInitialize(source, () => other);
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -43,6 +42,6 @@ public void OrInitialize_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<object, StructType>.First(new object());
 
         var actual = TaggedUnionExtensions.OrInitialize(source, () => other);
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs
index e77053eb..110892f9 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -14,7 +13,7 @@ public void OrInitializeAsync_OtherFactoryAsyncIsNull_ExpectArgumentNullExceptio
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.ThrowsAsync<ArgumentNullException>(async () => _ = await TaggedUnionExtensions.OrInitializeAsync(source, null!));
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public async Task OrInitializeAsync_SourceIsFirst_ExpectSource()
         var other = TaggedUnion<RefType?, StructType>.First(ZeroIdRefType);
 
         var actual = await TaggedUnionExtensions.OrInitializeAsync(source, () => Task.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public async Task OrInitializeAsync_SourceIsSecond_ExpectSource()
         var other = default(TaggedUnion<object, StructType>);
 
         var actual = await TaggedUnionExtensions.OrInitializeAsync(source, () => Task.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -44,6 +43,6 @@ public async Task OrInitializeAsync_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<int, RefType>.Second(new RefType());
 
         var actual = await TaggedUnionExtensions.OrInitializeAsync(source, () => Task.FromResult(other));
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs
index e9d5f04d..1f34ec7c 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/OrInitializeValueAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -14,7 +13,7 @@ public void OrInitializeValueAsync_OtherFactoryAsyncIsNull_ExpectArgumentNullExc
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.ThrowsAsync<ArgumentNullException>(async () => _ = await TaggedUnionExtensions.OrInitializeValueAsync(source, null!));
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public async Task OrInitializeValueAsync_SourceIsFirst_ExpectSource()
         var other = default(TaggedUnion<StructType, DateTime>);
 
         var actual = await TaggedUnionExtensions.OrInitializeValueAsync(source, () => ValueTask.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public async Task OrInitializeValueAsync_SourceIsSecond_ExpectSource()
         var other = TaggedUnion<object, StructType>.Second(SomeTextStructType);
 
         var actual = await TaggedUnionExtensions.OrInitializeValueAsync(source, () => ValueTask.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -44,6 +43,6 @@ public async Task OrInitializeValueAsync_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<RefType, object>.First(MinusFifteenIdRefType);
 
         var actual = await TaggedUnionExtensions.OrInitializeValueAsync(source, () => ValueTask.FromResult(other));
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/Test.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/Test.cs
similarity index 100%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Extensions.Obsolete.Test/Test.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Extensions.Obsolete.Test/Test.cs
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Static.Test/Equals.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Static.Test/Equals.cs
similarity index 90%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Static.Test/Equals.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Static.Test/Equals.cs
index d5ba1664..8ce98f12 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Static.Test/Equals.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Static.Test/Equals.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void Equals_UnionAIsDefaultAndUnionBIsDefault_ExpectTrue()
         var unionB = new TaggedUnion<StructType, RefType>();
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -26,7 +25,7 @@ public void Equals_UnionAFirstValueEqualsUnionBFirstValue_ExpectTrue(
         var unionB = TaggedUnion<object?, StructType>.First(sourceValue);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -47,7 +46,7 @@ public void Equals_UnionASecondValueEqualsUnionBSecondValue_ExpectTrue()
         var unionB = (TaggedUnion<RefType, StructType>)bValue;
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -57,7 +56,7 @@ public void Equals_UnionAIsDefaultAndUnionBIsFirst_ExpectFalse()
         var unionB = TaggedUnion<RefType?, StructType>.First(null);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -67,7 +66,7 @@ public void Equals_UnionAIsDefaultAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<object, StructType>.Second(default);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -77,7 +76,7 @@ public void Equals_UnionAIsFirstAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<RefType, StructType>);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -87,7 +86,7 @@ public void Equals_UnionAIsFirstAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<StructType, StructType>.Second(SomeTextStructType);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -97,7 +96,7 @@ public void Equals_UnionAIsSecondAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<StructType, RefType>);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -107,7 +106,7 @@ public void Equals_UnionAIsSecondAndUnionBIsFirst_ExpectFalse()
         var unionB = TaggedUnion<RefType, RefType>.First(ZeroIdRefType);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -128,7 +127,7 @@ public void Equals_UnionAFirstValueIsNotEqualUnionBFirstValue_ExpectFalse()
         var unionB = TaggedUnion<RefType, StructType?>.First(bValue);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -147,6 +146,6 @@ public void Equals_UnionASecondValueIsNotEqualUnionBSecondValue_ExpectFalse()
         var unionB = TaggedUnion<RefType, StructType>.Second(bValue);
 
         var actual = TaggedUnion.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Static.Test/Test.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Static.Test/Test.cs
similarity index 100%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Static.Test/Test.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Static.Test/Test.cs
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.Static.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.Static.cs
similarity index 90%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.Static.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.Static.cs
index 09f4d294..ffbcf648 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.Static.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.Static.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void EqualsStatic_UnionAIsDefaultAndUnionBIsDefault_ExpectTrue()
         var unionB = new TaggedUnion<RefType, StructType>();
 
         var actual = TaggedUnion<RefType, StructType>.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void EqualsStatic_UnionAFirstValueEqualsUnionBFirstValue_ExpectTrue()
         var unionB = (TaggedUnion<StructType, RefType?>)bValue;
 
         var actual = TaggedUnion<StructType, RefType?>.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -43,7 +42,7 @@ public void EqualsStatic_UnionASecondValueEqualsUnionBSecondValue_ExpectTrue()
         var unionB = (TaggedUnion<StructType, RefType?>)MinusFifteenIdRefType;
 
         var actual = TaggedUnion<StructType, RefType?>.Equals(unionA, unionB);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -53,7 +52,7 @@ public void EqualsStatic_UnionAIsDefaultAndUnionBIsFirst_ExpectFalse()
         var unionB = TaggedUnion<StructType, RefType>.First(default);
 
         var actual = TaggedUnion<StructType, RefType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -63,7 +62,7 @@ public void EqualsStatic_UnionAIsDefaultAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<StructType, RefType?>.Second(null);
 
         var actual = TaggedUnion<StructType, RefType?>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -73,7 +72,7 @@ public void EqualsStatic_UnionAIsFirstAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<StructType, RefType>);
 
         var actual = TaggedUnion<StructType, RefType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -83,7 +82,7 @@ public void EqualsStatic_UnionAIsFirstAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<RefType, RefType>.Second(PlusFifteenIdRefType);
 
         var actual = TaggedUnion<RefType, RefType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -93,7 +92,7 @@ public void EqualsStatic_UnionAIsSecondAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<StructType, RefType>);
 
         var actual = TaggedUnion<StructType, RefType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -103,7 +102,7 @@ public void EqualsStatic_UnionAIsSecondAndUnionBIsFirst_ExpectFalse()
         var unionB = TaggedUnion<StructType, StructType>.First(SomeTextStructType);
 
         var actual = TaggedUnion<StructType, StructType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -124,7 +123,7 @@ public void EqualsStatic_UnionAFirstValueIsNotEqualUnionBFirstValue_ExpectFalse(
         var unionB = TaggedUnion<RefType, StructType?>.First(bValue);
 
         var actual = TaggedUnion<RefType, StructType?>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -143,6 +142,6 @@ public void EqualsStatic_UnionASecondValueIsNotEqualUnionBSecondValue_ExpectFals
         var unionB = TaggedUnion<RefType, StructType>.Second(bValue);
 
         var actual = TaggedUnion<RefType, StructType>.Equals(unionA, unionB);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.cs
index 67dbc5b9..d905d451 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Equality.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Equality.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void Equality_UnionAIsDefaultAndUnionBIsDefault_ExpectTrue()
         var unionB = default(TaggedUnion<RefType, StructType>);
 
         var actual = unionA == unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void Equality_UnionAFirstValueEqualsUnionBFirstValue_ExpectTrue()
         var unionB = TaggedUnion<StructType, RefType?>.First(bValue);
 
         var actual = unionA == unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -43,7 +42,7 @@ public void Equality_UnionASecondValueEqualsUnionBSecondValue_ExpectTrue()
         var unionB = TaggedUnion<StructType?, RefType>.Second(ZeroIdRefType);
 
         var actual = unionA == unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -53,7 +52,7 @@ public void Equality_UnionAIsDefaultAndUnionBIsFirst_ExpectFalse()
         var unionB = default(TaggedUnion<StructType, RefType>);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -63,7 +62,7 @@ public void Equality_UnionAIsDefaultAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<RefType?, StructType>.Second(SomeTextStructType);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -73,7 +72,7 @@ public void Equality_UnionAIsFirstAndUnionBIsDefault_ExpectFalse()
         var unionB = TaggedUnion<StructType, RefType>.First(SomeTextStructType);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -83,7 +82,7 @@ public void Equality_UnionAIsFirstAndUnionBIsSecond_ExpectFalse()
         var unionB = TaggedUnion<StructType, StructType>.Second(SomeTextStructType);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -93,7 +92,7 @@ public void Equality_UnionAIsSecondAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<StructType, RefType>);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -103,7 +102,7 @@ public void Equality_UnionAIsSecondAndUnionBIsFirst_ExpectFalse()
         var unionB = TaggedUnion<RefType, RefType>.First(ZeroIdRefType);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -124,7 +123,7 @@ public void Equality_UnionAFirstValueIsNotEqualUnionBFirstValue_ExpectFalse()
         var unionB = TaggedUnion<RefType, StructType?>.First(bValue);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -143,6 +142,6 @@ public void Equality_UnionASecondValueIsNotEqualUnionBSecondValue_ExpectFalse()
         var unionB = TaggedUnion<RefType, StructType>.Second(bValue);
 
         var actual = unionA == unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityObject.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityObject.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityObject.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityObject.cs
index 34cab73c..79b038d7 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityObject.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityObject.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void EqualsWithObject_SourceIsDefaultAndObjectIsDefault_ExpectTrue()
         object? obj = new TaggedUnion<StructType, RefType>();
 
         var actual = source.Equals(obj);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public void EqualsWithObject_SourceFirstValueEqualsObjectFirstValue_ExpectTrue()
         object? obj = TaggedUnion<StructType?, RefType>.First(null);
 
         var actual = source.Equals(obj);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public void EqualsWithObject_SourceSecondValueEqualsObjectSecondValue_ExpectTrue
         object? obj = (TaggedUnion<StructType, RefType>)MinusFifteenIdRefType;
 
         var actual = source.Equals(obj);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -44,7 +43,7 @@ public void EqualsWithObject_SourceIsDefaultAndObjectIsFirst_ExpectFalse()
         object? obj = TaggedUnion<RefType?, StructType>.First(null);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -54,7 +53,7 @@ public void EqualsWithObject_SourceIsDefaultAndObjectIsSecond_ExpectFalse()
         object? obj = TaggedUnion<StructType, RefType>.Second(PlusFifteenIdRefType);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -64,7 +63,7 @@ public void EqualsWithObject_SourceIsFirstAndObjectIsDefault_ExpectFalse()
         object? obj = default(TaggedUnion<RefType, StructType>);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -74,7 +73,7 @@ public void EqualsWithObject_SourceIsFirstAndObjectIsSecond_ExpectFalse()
         object? obj = TaggedUnion<RefType?, RefType?>.Second(null);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -84,7 +83,7 @@ public void EqualsWithObject_SourceIsSecondAndObjectIsDefault_ExpectFalse()
         object? obj = default(TaggedUnion<StructType, RefType>);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -94,7 +93,7 @@ public void EqualsWithObject_SourceIsSecondAndObjectIsFirst_ExpectFalse()
         object? obj = TaggedUnion<StructType, StructType>.First(default);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -115,7 +114,7 @@ public void EqualsWithObject_SourceFirstValueIsNotEqualObjectFirstValue_ExpectFa
         object? obj = TaggedUnion<RefType?, StructType?>.First(objValue);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -130,7 +129,7 @@ public void EqualsWithObject_SourceSecondValueIsNotEqualObjectSecondValue_Expect
         object? obj = TaggedUnion<RefType, StructType?>.Second(null);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -145,7 +144,7 @@ public void EqualsWithObject_ObjectIsOtherTaggedUnion_ExpectFalse()
         object? obj = TaggedUnion<RefType, StructType>.Second(sourceValue);
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -157,7 +156,7 @@ public void EqualsWithObject_ObjectIsNotTaggedUnion_ExpectFalse()
         object? obj = sourceValue;
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -169,6 +168,6 @@ public void EqualsWithObject_ObjectIsNull_ExpectFalse()
         object? obj = null;
 
         var actual = source.Equals(obj);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityOther.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityOther.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityOther.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityOther.cs
index 7ac2e0cb..b2c31465 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/EqualityOther.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/EqualityOther.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void EqualsWithOther_SourceIsDefaultAndOtherIsDefault_ExpectTrue()
         var other = new TaggedUnion<StructType, RefType>();
 
         var actual = source.Equals(other);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public void EqualsWithOther_SourceFirstValueEqualsOtherFirstValue_ExpectTrue()
         var other = TaggedUnion<StructType?, RefType>.First(null);
 
         var actual = source.Equals(other);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public void EqualsWithOther_SourceSecondValueEqualsOtherSecondValue_ExpectTrue()
         var other = (TaggedUnion<StructType, RefType>)MinusFifteenIdRefType;
 
         var actual = source.Equals(other);
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -44,7 +43,7 @@ public void EqualsWithOther_SourceIsDefaultAndOtherIsFirst_ExpectFalse()
         var other = TaggedUnion<RefType?, StructType>.First(null);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -54,7 +53,7 @@ public void EqualsWithOther_SourceIsDefaultAndOtherIsSecond_ExpectFalse()
         var other = TaggedUnion<StructType, RefType>.Second(PlusFifteenIdRefType);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -64,7 +63,7 @@ public void EqualsWithOther_SourceIsFirstAndOtherIsDefault_ExpectFalse()
         var other = default(TaggedUnion<RefType, StructType>);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -74,7 +73,7 @@ public void EqualsWithOther_SourceIsFirstAndOtherIsSecond_ExpectFalse()
         var other = TaggedUnion<RefType?, RefType?>.Second(null);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -84,7 +83,7 @@ public void EqualsWithOther_SourceIsSecondAndOtherIsDefault_ExpectFalse()
         var other = default(TaggedUnion<StructType, RefType>);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -94,7 +93,7 @@ public void EqualsWithOther_SourceIsSecondAndOtherIsFirst_ExpectFalse()
         var other = TaggedUnion<StructType, StructType>.First(default);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -115,7 +114,7 @@ public void EqualsWithOther_SourceFirstValueIsNotEqualOtherFirstValue_ExpectFals
         var other = TaggedUnion<RefType?, StructType?>.First(otherValue);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -130,6 +129,6 @@ public void EqualsWithOther_SourceSecondValueIsNotEqualOtherSecondValue_ExpectFa
         var other = TaggedUnion<RefType, StructType?>.Second(null);
 
         var actual = source.Equals(other);
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/HashCode.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/HashCode.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/HashCode.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/HashCode.cs
index 2bca6844..a6598232 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/HashCode.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/HashCode.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -16,7 +15,7 @@ public void GetHashCode_SourceAndOtherAreDefault_ExpectValuesAreEqual()
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -30,7 +29,7 @@ public void GetHashCode_SourceFirstValueIsSameAsOtherFirstValue_ExpectValuesAreE
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -44,7 +43,7 @@ public void GetHashCode_SourceSecondValueIsSameAsOtherSecondValue_ExpectValuesAr
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -56,7 +55,7 @@ public void GetHashCode_SourceIsDefaultAndOtherIsNotDefault_ExpectValuesAreNotEq
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -70,7 +69,7 @@ public void GetHashCode_SourceFirstValueIsSameAsOtherSecondValue_ExpectValuesAre
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -82,7 +81,7 @@ public void GetHashCode_SourceFirstValueAreNotEqualOtherFirstValue_ExpectValuesA
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -104,7 +103,7 @@ public void GetHashCode_SourceSecondValueIsNotSameAsOtherSecondValue_ExpectValue
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -118,7 +117,7 @@ public void GetHashCode_SourceFirstValueIsSameAsOtherFirstButSecondTypesAreNotEq
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -132,7 +131,7 @@ public void GetHashCode_SourceSecondValueIsSameAsOtherSecondButFirstTypesAreNotE
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 
     [Test]
@@ -144,6 +143,6 @@ public void GetHashCode_SourceAndOtherAreDefaultButTypesAreNotEqual_ExpectValues
         var sourceHashCode = source.GetHashCode();
         var otherHashCode = other.GetHashCode();
 
-        Assert.AreNotEqual(sourceHashCode, otherHashCode);
+        ClassicAssert.AreNotEqual(sourceHashCode, otherHashCode);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Inequality.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Inequality.cs
similarity index 88%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Inequality.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Inequality.cs
index 8246ab2d..51afb32a 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Equality/Inequality.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Equality/Inequality.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void Inequality_UnionAIsDefaultAndUnionBIsFirst_ExpectTrue()
         var unionB = default(TaggedUnion<RefType, StructType>);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public void Inequality_UnionAIsDefaultAndUnionBIsSecond_ExpectTrue()
         var unionB = TaggedUnion<RefType?, StructType?>.Second(null);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public void Inequality_UnionAIsFirstAndUnionBIsDefault_ExpectTrue()
         var unionB = TaggedUnion<StructType, RefType>.First(default);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -44,7 +43,7 @@ public void Inequality_UnionAIsFirstAndUnionBIsSecond_ExpectTrue()
         var unionB = TaggedUnion<StructType, StructType>.Second(SomeTextStructType);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -54,7 +53,7 @@ public void Inequality_UnionAIsSecondAndUnionBIsDefault_ExpectTrue()
         var unionB = default(TaggedUnion<RefType, StructType>);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -64,7 +63,7 @@ public void Inequality_UnionAIsSecondAndUnionBIsFirst_ExpectTrue()
         var unionB = TaggedUnion<RefType?, RefType?>.First(null);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -77,7 +76,7 @@ public void Inequality_UnionAFirstValueIsNotEqualUnionBFirstValue_ExpectTrue()
         var unionB = TaggedUnion<object, StructType?>.First(bValue);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -87,7 +86,7 @@ public void Inequality_UnionASecondValueIsNotEqualUnionBSecondValue_ExpectTrue()
         var unionB = TaggedUnion<RefType, StructType?>.Second(SomeTextStructType);
 
         var actual = unionA != unionB;
-        Assert.True(actual);
+        ClassicAssert.True(actual);
     }
 
     [Test]
@@ -97,7 +96,7 @@ public void InInequality_UnionAIsDefaultAndUnionBIsDefault_ExpectFalse()
         var unionB = default(TaggedUnion<RefType, StructType>);
 
         var actual = unionA != unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -116,7 +115,7 @@ public void Inequality_UnionAFirstValueEqualsUnionBFirstValue_ExpectFalse()
         var unionB = TaggedUnion<StructType, RefType?>.First(bValue);
 
         var actual = unionA != unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 
     [Test]
@@ -126,6 +125,6 @@ public void Inequality_UnionASecondValueEqualsUnionBSecondValue_ExpectFalse()
         var unionB = TaggedUnion<StructType?, RefType>.Second(MinusFifteenIdRefType);
 
         var actual = unionA != unionB;
-        Assert.False(actual);
+        ClassicAssert.False(actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs
index 2786607e..a184748f 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void First_Constructor_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<object?, RefType>(sourceValue);
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs
index ad117bb2..236b9f24 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Constructor.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void Second_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<StructType, object?>(sourceValue);
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs
similarity index 70%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs
index 7ab5806c..c39ba374 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Default.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -11,6 +10,6 @@ partial class TaggedUnionTest
     public void Default_ExpectIsInitializedGetsFalse()
     {
         var taggedUnion = default(TaggedUnion<RefType?, StructType?>);
-        Assert.False(taggedUnion.IsInitialized);
+        ClassicAssert.False(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs
similarity index 71%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs
index fb83310c..67f68434 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.DefaultConstructor.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -11,6 +10,6 @@ partial class TaggedUnionTest
     public void DefaultConstructor_ExpectIsInitializedGetsFalse()
     {
         var taggedUnion = new TaggedUnion<RefType?, StructType?>();
-        Assert.False(taggedUnion.IsInitialized);
+        ClassicAssert.False(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs
index 487d150d..8f468ff1 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void First_Explicit_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<object?, RefType>.First(sourceValue);
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs
index 88a46c5a..c813771d 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Explicit.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void Second_Explicit_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<StructType, object?>.Second(sourceValue);
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs
index 7ec563b9..525aa8b5 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.Alt.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void First_Implicit_Alt_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, StructType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs
index c0cfed1c..6a19f163 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void First_Implicit_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, RefType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs
index a47fd014..66b5172c 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.Alt.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void Second_Implicit_Alt_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<RefType, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs
similarity index 78%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs
index a8f58aea..92d26748 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory.Obsolete/Factory.Implicit.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -13,6 +12,6 @@ public void Second_Implicit_ExpectIsInitializedGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<StructType, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsInitialized);
+        ClassicAssert.True(taggedUnion.IsInitialized);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.First.cs
similarity index 83%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.First.cs
index 75aaa9a5..cc951d83 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,14 +12,14 @@ public void First_Constructor_ExpectIsFirstGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<object?, StructType>(sourceValue);
-        Assert.True(taggedUnion.IsFirst);
+        ClassicAssert.True(taggedUnion.IsFirst);
     }
 
     [Test]
     public void First_Constructor_ExpectIsSecondGetsFalse()
     {
         var taggedUnion = new TaggedUnion<StructType, RefType>(SomeTextStructType);
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void First_Constructor_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<object?, RefType>(sourceValue);
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void First_Constructor_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<object?, RefType>(sourceValue);
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs
index 7367ede9..c4914a8c 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Constructor.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -11,7 +10,7 @@ partial class TaggedUnionTest
     public void Second_ExpectIsFirstGetsFalse()
     {
         var taggedUnion = new TaggedUnion<StructType, RefType?>(PlusFifteenIdRefType);
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
@@ -20,7 +19,7 @@ public void Second_ExpectIsSecondGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<RefType?, object?>(sourceValue);
-        Assert.True(taggedUnion.IsSecond);
+        ClassicAssert.True(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void Second_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<StructType, object?>(sourceValue);
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void Second_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = new TaggedUnion<StructType, object?>(sourceValue);
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Default.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Default.cs
similarity index 73%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Default.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Default.cs
index da235d56..9c3d3b42 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Default.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Default.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -10,27 +9,27 @@ partial class TaggedUnionTest
     public void Default_ExpectIsFirstGetsFalse()
     {
         var taggedUnion = default(TaggedUnion<RefType?, StructType>);
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
     public void Default_ExpectIsSecondGetsFalse()
     {
         var taggedUnion = default(TaggedUnion<StructType?, RefType>);
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
     public void Default_ExpectIsNoneGetsTrue()
     {
         var taggedUnion = default(TaggedUnion<RefType?, StructType?>);
-        Assert.True(taggedUnion.IsNone);
+        ClassicAssert.True(taggedUnion.IsNone);
     }
 
     [Test]
     public void Default_ExpectIsNotNoneGetsFalse()
     {
         var taggedUnion = default(TaggedUnion<RefType?, StructType?>);
-        Assert.False(taggedUnion.IsNotNone);
+        ClassicAssert.False(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs
similarity index 74%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs
index 15fb0b1b..62b4996b 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.DefaultConstructor.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 
 namespace PrimeFuncPack.Core.Tests;
@@ -10,27 +9,27 @@ partial class TaggedUnionTest
     public void DefaultConstructor_ExpectIsFirstGetsFalse()
     {
         var taggedUnion = new TaggedUnion<RefType?, StructType>();
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
     public void DefaultConstructor_ExpectIsSecondGetsFalse()
     {
         var taggedUnion = new TaggedUnion<StructType?, RefType>();
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
     public void DefaultConstructor_ExpectIsNoneGetsTrue()
     {
         var taggedUnion = new TaggedUnion<RefType?, StructType?>();
-        Assert.True(taggedUnion.IsNone);
+        ClassicAssert.True(taggedUnion.IsNone);
     }
 
     [Test]
     public void DefaultConstructor_ExpectIsNotNoneGetsFalse()
     {
         var taggedUnion = new TaggedUnion<RefType?, StructType?>();
-        Assert.False(taggedUnion.IsNotNone);
+        ClassicAssert.False(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.First.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.First.cs
index 5e828a17..21833e24 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,14 +12,14 @@ public void First_Explicit_ExpectIsFirstGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<object?, StructType>.First(sourceValue);
-        Assert.True(taggedUnion.IsFirst);
+        ClassicAssert.True(taggedUnion.IsFirst);
     }
 
     [Test]
     public void First_Explicit_ExpectIsSecondGetsFalse()
     {
         var taggedUnion = TaggedUnion<StructType, RefType>.First(SomeTextStructType);
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void First_Explicit_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<object?, RefType>.First(sourceValue);
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void First_Explicit_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<object?, RefType>.First(sourceValue);
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs
similarity index 83%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs
index 74e30125..056b6f8e 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Explicit.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -11,7 +10,7 @@ partial class TaggedUnionTest
     public void Second_Explicit_ExpectIsFirstGetsFalse()
     {
         var taggedUnion = TaggedUnion<StructType, RefType?>.Second(PlusFifteenIdRefType);
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
@@ -20,7 +19,7 @@ public void Second_Explicit_ExpectIsSecondGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<RefType?, object?>.Second(sourceValue);
-        Assert.True(taggedUnion.IsSecond);
+        ClassicAssert.True(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void Second_Explicit_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<StructType, object?>.Second(sourceValue);
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void Second_Explicit_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         var taggedUnion = TaggedUnion<StructType, object?>.Second(sourceValue);
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs
index 6bbe4d96..07c6e982 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.Alt.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,14 +12,14 @@ public void First_Implicit_Alt_ExpectIsFirstGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, RefType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsFirst);
+        ClassicAssert.True(taggedUnion.IsFirst);
     }
 
     [Test]
     public void First_Implicit_Alt_ExpectIsSecondGetsFalse()
     {
         TaggedUnion<RefType, StructType> taggedUnion = MinusFifteenIdRefType;
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void First_Implicit_Alt_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         TaggedUnion<object?, StructType> taggedUnion = sourceValue;
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void First_Implicit_Alt_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, StructType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.cs
index ebedf99e..c30793a1 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,14 +12,14 @@ public void First_Implicit_ExpectIsFirstGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, StructType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsFirst);
+        ClassicAssert.True(taggedUnion.IsFirst);
     }
 
     [Test]
     public void First_Implicit_ExpectIsSecondGetsFalse()
     {
         TaggedUnion<StructType, RefType> taggedUnion = SomeTextStructType;
-        Assert.False(taggedUnion.IsSecond);
+        ClassicAssert.False(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void First_Implicit_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         TaggedUnion<object?, RefType> taggedUnion = sourceValue;
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void First_Implicit_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<object?, RefType> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs
index 4527b8a6..e40b08f2 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.Alt.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -11,7 +10,7 @@ partial class TaggedUnionTest
     public void Second_Implicit_Alt_ExpectIsFirstGetsFalse()
     {
         TaggedUnion<StructType?, RefType> taggedUnion = ZeroIdRefType;
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
@@ -20,7 +19,7 @@ public void Second_Implicit_Alt_ExpectIsSecondGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<StructType, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsSecond);
+        ClassicAssert.True(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void Second_Implicit_Alt_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         TaggedUnion<RefType, object?> taggedUnion = sourceValue;
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void Second_Implicit_Alt_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<RefType, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs
index e3b68805..a083b166 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Factory/Factory.Implicit.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -11,7 +10,7 @@ partial class TaggedUnionTest
     public void Second_Implicit_ExpectIsFirstGetsFalse()
     {
         TaggedUnion<StructType, RefType?> taggedUnion = PlusFifteenIdRefType;
-        Assert.False(taggedUnion.IsFirst);
+        ClassicAssert.False(taggedUnion.IsFirst);
     }
 
     [Test]
@@ -20,7 +19,7 @@ public void Second_Implicit_ExpectIsSecondGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<RefType?, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsSecond);
+        ClassicAssert.True(taggedUnion.IsSecond);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public void Second_Implicit_ExpectIsNoneGetsFalse(
         object? sourceValue)
     {
         TaggedUnion<StructType, object?> taggedUnion = sourceValue;
-        Assert.False(taggedUnion.IsNone);
+        ClassicAssert.False(taggedUnion.IsNone);
     }
 
     [Test]
@@ -38,6 +37,6 @@ public void Second_Implicit_ExpectIsNotNoneGetsTrue(
         object? sourceValue)
     {
         TaggedUnion<StructType, object?> taggedUnion = sourceValue;
-        Assert.True(taggedUnion.IsNotNone);
+        ClassicAssert.True(taggedUnion.IsNotNone);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.Other.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.Other.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.Other.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.Other.cs
index 9105fca6..7ed1f8a6 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.Other.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.Other.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -16,7 +15,7 @@ public void FoldWithOther_MapFirstIsNull_ExpectArgumentNullException()
         var other = int.MaxValue;
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(null!, _ => second, other));
-        Assert.AreEqual("mapFirst", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirst", ex!.ParamName);
     }
 
     [Test]
@@ -28,7 +27,7 @@ public void FoldWithOther_MapSecondIsNull_ExpectArgumentNullException()
         var other = TabString;
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(_ => first, null!, other));
-        Assert.AreEqual("mapSecond", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecond", ex!.ParamName);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public void FoldWithOther_SourceIsDefault_ExpectOther(
         var second = new { Id = 251 };
 
         var actual = source.Fold(_ => first, _ => second, other);
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -55,7 +54,7 @@ public void FoldWithOther_SourceIsFirst_ExpectFirstResult()
         var other = PlusFifteenIdRefType;
 
         var actual = source.Fold(_ => first, _ => second, other);
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -68,6 +67,6 @@ public void FoldWithOther_SourceIsSecond_ExpectSecondResult()
         var other = PlusFifteenIdRefType;
 
         var actual = source.Fold(_ => first, _ => second, other);
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.OtherFactory.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.OtherFactory.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.OtherFactory.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.OtherFactory.cs
index 70b9b630..93d8a54b 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.OtherFactory.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.OtherFactory.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -16,7 +15,7 @@ public void FoldWithOtherFactory_MapFirstIsNull_ExpectArgumentNullException()
         var other = MinusFifteenIdRefType;
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(null!, _ => second, () => other));
-        Assert.AreEqual("mapFirst", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirst", ex!.ParamName);
     }
 
     [Test]
@@ -28,7 +27,7 @@ public void FoldWithOtherFactory_MapSecondIsNull_ExpectArgumentNullException()
         var other = new object();
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(_ => first, null!, () => other));
-        Assert.AreEqual("mapSecond", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecond", ex!.ParamName);
     }
 
     [Test]
@@ -40,7 +39,7 @@ public void FoldWithOtherFactory_OtherFactoryIsNull_ExpectArgumentNullException(
         var second = decimal.MaxValue;
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(_ => first, _ => second, null!));
-        Assert.AreEqual("otherFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactory", ex!.ParamName);
     }
 
     [Test]
@@ -53,7 +52,7 @@ public void FoldWithOtherFactory_SourceIsDefault_ExpectOther()
         var other = new { Id = 515 };
 
         var actual = source.Fold(_ => first, _ => second, () => other);
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -66,7 +65,7 @@ public void FoldWithOtherFactory_SourceIsFirst_ExpectFirstResult()
         var other = int.MinValue;
 
         var actual = source.Fold(_ => first, _ => second, () => other);
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -79,6 +78,6 @@ public void FoldWithOtherFactory_SourceIsSecond_ExpectSecondResult()
         var other = PlusFifteenIdRefType;
 
         var actual = source.Fold(_ => first, _ => second, () => other);
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.cs
similarity index 84%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.cs
index a7e0e09e..7684f231 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/Fold.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/Fold.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void Fold_MapFirstIsNull_ExpectArgumentNullException()
         var source = TaggedUnion<RefType, StructType>.First(PlusFifteenIdRefType);
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(null!, _ => new object()));
-        Assert.AreEqual("mapFirst", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirst", ex!.ParamName);
     }
 
     [Test]
@@ -22,7 +21,7 @@ public void Fold_MapSecondIsNull_ExpectArgumentNullException()
         var source = TaggedUnion<RefType, StructType>.First(PlusFifteenIdRefType);
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Fold(_ => new object(), null!));
-        Assert.AreEqual("mapSecond", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecond", ex!.ParamName);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public void Fold_SourceIsDefault_ExpectDefault()
         var second = MinusFifteenIdRefType;
 
         var actual = source.Fold(_ => first, _ => second);
-        Assert.IsNull(actual);
+        ClassicAssert.IsNull(actual);
     }
 
     [Test]
@@ -46,7 +45,7 @@ public void Fold_SourceIsFirst_ExpectFirstResult()
         var second = NullTextStructType;
 
         var actual = source.Fold(_ => first, _ => second);
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -58,6 +57,6 @@ public void Fold_SourceIsSecond_ExpectSecondResult()
         var second = ZeroIdRefType;
 
         var actual = source.Fold(_ => first, _ => second);
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.Other.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.Other.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.Other.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.Other.cs
index bd13f3e4..add1eca7 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.Other.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.Other.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -19,7 +18,7 @@ public void FoldAsyncWithOther_MapFirstAsyncIsNull_ExpectArgumentNullException()
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldAsync(null!, _ => Task.FromResult(second), other));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void FoldAsyncWithOther_MapSecondAsyncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldAsync(_ => Task.FromResult(first), null!, other));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -46,7 +45,7 @@ public async Task FoldAsyncWithOther_SourceIsDefault_ExpectOther()
         object other = SomeString;
 
         var actual = await source.FoldAsync(_ => Task.FromResult(first), _ => Task.FromResult(second), other);
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -59,7 +58,7 @@ public async Task FoldAsyncWithOther_SourceIsFirst_ExpectFirstResult()
         var other = PlusFifteenIdRefType;
 
         var actual = await source.FoldAsync(_ => Task.FromResult(first), _ => Task.FromResult(second), other);
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -72,6 +71,6 @@ public async Task FoldAsyncWithOther_SourceIsSecond_ExpectSecondResult()
         StructType? other = null;
 
         var actual = await source.FoldAsync(_ => Task.FromResult(first), _ => Task.FromResult(second), other);
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs
similarity index 88%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs
index b1d63d94..0eea1a68 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactory.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -19,7 +18,7 @@ public void FoldAsyncWithOtherFactory_MapFirstAsyncIsNull_ExpectArgumentNullExce
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldAsync(null!, _ => Task.FromResult(second), () => other));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void FoldAsyncWithOtherFactory_MapSecondAsyncIsNull_ExpectArgumentNullExc
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldAsync(_ => Task.FromResult(first), null!, () => other));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -49,7 +48,7 @@ public void FoldAsyncWithOtherFactory_OtherFactoryIsNull_ExpectArgumentNullExcep
             async () => _ = await source.FoldAsync(
                 _ => Task.FromResult(first), _ => Task.FromResult(second), otherFactory));
 
-        Assert.AreEqual("otherFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactory", ex!.ParamName);
     }
 
     [Test]
@@ -64,7 +63,7 @@ public async Task FoldAsyncWithOtherFactory_SourceIsDefault_ExpectOther()
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => other);
 
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -79,7 +78,7 @@ public async Task FoldAsyncWithOtherFactory_SourceIsFirst_ExpectFirstResult()
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => other);
 
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -94,6 +93,6 @@ public async Task FoldAsyncWithOtherFactory_SourceIsSecond_ExpectSecondResult()
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => other);
 
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs
index c0efee7e..f14b7e38 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldAsync.OtherFactoryAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -20,7 +19,7 @@ public void FoldAsyncWithOtherFactoryAsync_MapFirstAsyncIsNull_ExpectArgumentNul
             async () => _ = await source.FoldAsync(
                 null!, _ => Task.FromResult(second), () => Task.FromResult(other)));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -35,7 +34,7 @@ public void FoldAsyncWithOtherFactoryAsync_MapSecondAsyncIsNull_ExpectArgumentNu
             async () => _ = await source.FoldAsync(
                 _ => Task.FromResult(first), null!, () => Task.FromResult(other)));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -51,7 +50,7 @@ public void FoldAsyncWithOtherFactoryAsync_OtherFactoryAsyncIsNull_ExpectArgumen
             async () => _ = await source.FoldAsync(
                 _ => Task.FromResult(first), _ => Task.FromResult(second), otherFactoryAsync));
 
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -66,7 +65,7 @@ public async Task FoldAsyncWithOtherFactoryAsync_SourceIsDefault_ExpectOther()
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => Task.FromResult(other));
 
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -81,7 +80,7 @@ public async Task FoldAsyncWithOtherFactoryAsync_SourceIsFirst_ExpectFirstResult
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => Task.FromResult(other));
 
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -96,6 +95,6 @@ public async Task FoldAsyncWithOtherFactoryAsync_SourceIsSecond_ExpectSecondResu
         var actual = await source.FoldAsync(
             _ => Task.FromResult(first), _ => Task.FromResult(second), () => Task.FromResult(other));
 
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs
similarity index 88%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs
index 44b51797..25e0cc54 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.Other.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -19,7 +18,7 @@ public void FoldValueAsyncWithOther_MapFirstAsyncIsNull_ExpectArgumentNullExcept
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldValueAsync(null!, _ => ValueTask.FromResult(second), other));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void FoldValueAsyncWithOther_MapSecondAsyncIsNull_ExpectArgumentNullExcep
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldValueAsync(_ => ValueTask.FromResult(first), null!, other));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -48,7 +47,7 @@ public async Task FoldValueAsyncWithOther_SourceIsDefault_ExpectOther()
         var actual = await source.FoldValueAsync(
             _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), other);
 
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -62,7 +61,7 @@ public async Task FoldValueAsyncWithOther_SourceIsFirst_ExpectFirstResult()
         var actual = await source.FoldValueAsync(
             static _ => default(ValueTask<RefType>), _ => ValueTask.FromResult(second), other);
 
-        Assert.IsNull(actual);
+        ClassicAssert.IsNull(actual);
     }
 
     [Test]
@@ -79,6 +78,6 @@ public async Task FoldValueAsyncWithOther_SourceIsSecond_ExpectSecondResult()
             _ => ValueTask.FromResult(second),
             other);
 
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs
index 3f1d7970..52d60495 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactory.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -19,7 +18,7 @@ public void FoldValueAsyncWithOtherFactory_MapFirstAsyncIsNull_ExpectArgumentNul
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldValueAsync(null!, _ => ValueTask.FromResult(second), () => other));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void FoldValueAsyncWithOtherFactory_MapSecondAsyncIsNull_ExpectArgumentNu
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.FoldValueAsync(_ => ValueTask.FromResult(first), null!, () => other));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -49,7 +48,7 @@ public void FoldValueAsyncWithOtherFactory_OtherFactoryIsNull_ExpectArgumentNull
             async () => _ = await source.FoldValueAsync(
                 _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), otherFactory));
 
-        Assert.AreEqual("otherFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactory", ex!.ParamName);
     }
 
     [Test]
@@ -64,7 +63,7 @@ public async Task FoldValueAsyncWithOtherFactory_SourceIsDefault_ExpectOther()
         var actual = await source.FoldValueAsync(
             _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), () => other);
 
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -79,7 +78,7 @@ public async Task FoldValueAsyncWithOtherFactory_SourceIsFirst_ExpectFirstResult
         var actual = await source.FoldValueAsync(
             _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), () => other);
 
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -94,6 +93,6 @@ public async Task FoldValueAsyncWithOtherFactory_SourceIsSecond_ExpectSecondResu
         var actual = await source.FoldValueAsync(
             _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), () => other);
 
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs
index 3dcb346e..15ae2e71 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Fold/FoldValueAsync.OtherFactoryAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -20,7 +19,7 @@ public void FoldValueAsyncWithOtherFactoryAsync_MapFirstAsyncIsNull_ExpectArgume
             async () => _ = await source.FoldValueAsync(
                 null!, _ => ValueTask.FromResult(second), () => ValueTask.FromResult(other)));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -35,7 +34,7 @@ public void FoldValueAsyncWithOtherFactoryAsync_MapSecondAsyncIsNull_ExpectArgum
             async () => _ = await source.FoldValueAsync(
                 _ => ValueTask.FromResult(first), null!, () => ValueTask.FromResult(other)));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -51,7 +50,7 @@ public void FoldValueAsyncWithOtherFactoryAsync_OtherFactoryAsyncIsNull_ExpectAr
             async () => _ = await source.FoldValueAsync(
                 _ => ValueTask.FromResult(first), _ => ValueTask.FromResult(second), otherFactoryAsync));
 
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -68,7 +67,7 @@ public async Task FoldValueAsyncWithOtherFactoryAsync_SourceIsDefault_ExpectOthe
             _ => ValueTask.FromResult(second),
             () => ValueTask.FromResult(other));
 
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 
     [Test]
@@ -85,7 +84,7 @@ public async Task FoldValueAsyncWithOtherFactoryAsync_SourceIsFirst_ExpectFirstR
             _ => ValueTask.FromResult(second),
             () => ValueTask.FromResult(other));
 
-        Assert.AreEqual(first, actual);
+        ClassicAssert.AreEqual(first, actual);
     }
 
     [Test]
@@ -102,6 +101,6 @@ public async Task FoldValueAsyncWithOtherFactoryAsync_SourceIsSecond_ExpectSecon
             _ => ValueTask.FromResult(second),
             () => ValueTask.FromResult(other));
 
-        Assert.AreEqual(second, actual);
+        ClassicAssert.AreEqual(second, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/Map.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/Map.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/Map.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/Map.cs
index 9b070f80..f04ecb39 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/Map.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/Map.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -15,7 +14,7 @@ public void Map_MapFirstFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.Throws<ArgumentNullException>(
             () => _ = source.Map<object, StructType>(null!, _ => SomeTextStructType));
 
-        Assert.AreEqual("mapFirst", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirst", ex!.ParamName);
     }
 
     [Test]
@@ -26,7 +25,7 @@ public void Map_MapSecondFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.Throws<ArgumentNullException>(
             () => _ = source.Map<int, StructType>(_ => 275, null!));
 
-        Assert.AreEqual("mapSecond", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecond", ex!.ParamName);
     }
 
     [Test]
@@ -41,7 +40,7 @@ public void Map_SourceIsFirst_ExpectMapppedValueFirstUnion()
         var actual = source.Map(_ => mappedFirst, _ => mappedSecond);
 
         var expected = TaggedUnion<RefType, string>.First(mappedFirst);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -56,7 +55,7 @@ public void Map_SourceIsSecond_ExpectMappedValueSecondUnion()
         var actual = source.Map(_ => mappedFirst, _ => mappedSecond);
 
         var expected = TaggedUnion<string, RefType>.Second(mappedSecond);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -70,6 +69,6 @@ public void Map_SourceIsDefault_ExpectDefault()
         var actual = source.Map(_ => mappedFirst, _ => mappedSecond);
 
         var expected = default(TaggedUnion<StructType, int>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapAsync.cs
similarity index 88%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapAsync.cs
index bdb0df05..d78dc6ec 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapAsync_MapFirstAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapAsync<object, string>(null!, _ => Task.FromResult(SomeString)));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -27,7 +26,7 @@ public void MapAsync_MapSecondAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapAsync<decimal, object>(_ => Task.FromResult(21.5m), null!));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public async Task MapAsync_SourceIsFirst_ExpectMapppedValueFirstUnion()
         var actual = await source.MapAsync(_ => Task.FromResult(mappedFirst), _ => Task.FromResult(mappedSecond));
 
         var expected = TaggedUnion<RefType, string>.First(mappedFirst);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -57,7 +56,7 @@ public async Task MapAsync_SourceIsSecond_ExpectMappedValueSecondUnion()
         var actual = await source.MapAsync(_ => Task.FromResult(mappedFirst), _ => Task.FromResult(mappedSecond));
 
         var expected = TaggedUnion<RefType, object>.Second(mappedSecond);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -71,6 +70,6 @@ public async Task MapAsync_SourceIsDefault_ExpectDefault()
         var actual = await source.MapAsync(_ => Task.FromResult(mappedFirst), _ => Task.FromResult(mappedSecond));
 
         var expected = default(TaggedUnion<StructType, RefType>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapValueAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapValueAsync.cs
similarity index 89%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapValueAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapValueAsync.cs
index dfcada83..fd13da8a 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Map/MapValueAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Map/MapValueAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapValueAsync_MapFirstAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapValueAsync<byte, int>(null!, _ => ValueTask.FromResult(157)));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -27,7 +26,7 @@ public void MapValueAsync_MapSecondAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapValueAsync<uint, DateTime>(_ => ValueTask.FromResult<uint>(1), null!));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -44,7 +43,7 @@ public async Task MapValueAsync_SourceIsFirst_ExpectMapppedValueFirstUnion()
             _ => ValueTask.FromResult(mappedSecond));
 
         var expected = TaggedUnion<StructType, RefType>.First(mappedFirst);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -61,7 +60,7 @@ public async Task MapValueAsync_SourceIsSecond_ExpectMappedValueSecondUnion()
             _ => ValueTask.FromResult(mappedSecond));
 
         var expected = TaggedUnion<DateTime, object?>.Second(mappedSecond);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -77,6 +76,6 @@ public async Task MapValueAsync_SourceIsDefault_ExpectDefault()
             _ => ValueTask.FromResult(mappedSecond));
 
         var expected = default(TaggedUnion<StructType, object>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirst.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirst.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirst.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirst.cs
index b941dcc4..0ac83af5 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirst.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirst.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void MapFirst_MapFirstFuncIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.MapFirst<int>(null!));
-        Assert.AreEqual("mapFirst", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirst", ex!.ParamName);
     }
 
     [Test]
@@ -26,7 +25,7 @@ public void MapFirst_SourceIsFirst_ExpectMappedValueFirstUnion()
         var actual = source.MapFirst(_ => mappedValue);
 
         var expected = TaggedUnion<RefType, object?>.First(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -39,7 +38,7 @@ public void MapFirst_SourceIsSecond_ExpectSourceValueSecondUnion()
         var actual = source.MapFirst(_ => mappedValue);
 
         var expected = TaggedUnion<string, object?>.Second(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -51,6 +50,6 @@ public void MapFirst_SourceIsDefault_ExpectDefault()
         var actual = source.MapFirst(_ => mappedValue);
 
         var expected = default(TaggedUnion<int, StructType?>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstAsync.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstAsync.cs
index dc1eeb2a..a77b675b 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapFirstAsync_MapFirstAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapFirstAsync<int>(null!));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public async Task MapFirstAsync_SourceIsFirst_ExpectMappedValueFirstUnion()
         var actual = await source.MapFirstAsync(_ => Task.FromResult(mappedValue));
 
         var expected = TaggedUnion<StructType?, object>.First(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public async Task MapFirstAsync_SourceIsSecond_ExpectSourceValueSecondUnion()
         var actual = await source.MapFirstAsync(_ => Task.FromResult(mappedValue));
 
         var expected = TaggedUnion<string, object?>.Second(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -54,6 +53,6 @@ public async Task MapFirstAsync_SourceIsDefault_ExpectDefault()
         var actual = await source.MapFirstAsync(_ => Task.FromResult(mappedValue));
 
         var expected = default(TaggedUnion<RefType, StructType?>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs
index a7e4c8ac..f5db7b90 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapFirst/MapFirstValueAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapFirstValueAsync_MapFirstValueAsyncFuncIsNull_ExpectArgumentNullEx
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapFirstValueAsync<decimal>(null!));
 
-        Assert.AreEqual("mapFirstAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapFirstAsync", ex!.ParamName);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public async Task MapFirstValueAsync_SourceIsFirst_ExpectMappedValueFirstUnion()
         var actual = await source.MapFirstValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = TaggedUnion<StructType, RefType>.First(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public async Task MapFirstValueAsync_SourceIsSecond_ExpectSourceValueSecondUnion
         var actual = await source.MapFirstValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = TaggedUnion<RefType, object>.Second(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -54,6 +53,6 @@ public async Task MapFirstValueAsync_SourceIsDefault_ExpectDefault()
         var actual = await source.MapFirstValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = default(TaggedUnion<RefType, RefType?>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecond.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecond.cs
similarity index 86%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecond.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecond.cs
index 4e09c1f5..5d86f094 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecond.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecond.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void MapSecond_MapSecondFuncIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.MapSecond<object>(null!));
-        Assert.AreEqual("mapSecond", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecond", ex!.ParamName);
     }
 
     [Test]
@@ -26,7 +25,7 @@ public void MapSecond_SourceIsFirst_ExpectSourceValueFirstUnion()
         var actual = source.MapSecond(_ => mappedValue);
 
         var expected = TaggedUnion<StructType?, RefType>.First(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -39,7 +38,7 @@ public void MapSecond_SourceIsSecond_ExpectMappedValueSecondUnion()
         var actual = source.MapSecond(_ => mappedValue);
 
         var expected = TaggedUnion<StructType, RefType>.Second(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -51,6 +50,6 @@ public void MapSecond_SourceIsDefault_ExpectDefault()
         var actual = source.MapSecond(_ => mappedValue);
 
         var expected = default(TaggedUnion<StructType, int>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondAsync.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondAsync.cs
index b4a3fb69..822d0c1c 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapSecondAsync_MapSecondAsyncFuncIsNull_ExpectArgumentNullException(
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapSecondAsync<int>(null!));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public async Task MapSecondAsync_SourceIsFirst_ExpectSourceValueFirstUnion()
         var actual = await source.MapSecondAsync(_ => Task.FromResult(mappedValue));
 
         var expected = TaggedUnion<RefType?, StructType>.First(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public async Task MapSecondAsync_SourceIsSecond_ExpectMapppedValueSecondUnion()
         var actual = await source.MapSecondAsync(_ => Task.FromResult(mappedValue));
 
         var expected = TaggedUnion<string, object>.Second(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -54,6 +53,6 @@ public async Task MapSecondAsync_SourceIsDefault_ExpectDefault()
         var actual = await source.MapSecondAsync(_ => Task.FromResult(mappedValue));
 
         var expected = default(TaggedUnion<object, StructType>);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs
similarity index 87%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs
index c7e6e10b..4b4db740 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/MapSecond/MapSecondValueAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -16,7 +15,7 @@ public void MapSecondValueAsync_MapSecondValueAsyncFuncIsNull_ExpectArgumentNull
         var ex = Assert.ThrowsAsync<ArgumentNullException>(
             async () => _ = await source.MapSecondValueAsync<int>(null!));
 
-        Assert.AreEqual("mapSecondAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("mapSecondAsync", ex!.ParamName);
     }
 
     [Test]
@@ -29,7 +28,7 @@ public async Task MapSecondValueAsync_SourceIsFirst_ExpectSourceValueFirstUnion(
         var actual = await source.MapSecondValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = TaggedUnion<string, RefType?>.First(sourceValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -42,7 +41,7 @@ public async Task MapSecondValueAsync_SourceIsSecond_ExpectMapppedValueSecondUni
         var actual = await source.MapSecondValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = TaggedUnion<object, RefType>.Second(mappedValue);
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -54,6 +53,6 @@ public async Task MapSecondValueAsync_SourceIsDefault_ExpectDefault()
         var actual = await source.MapSecondValueAsync(_ => ValueTask.FromResult(mappedValue));
 
         var expected = new TaggedUnion<StructType, RefType>();
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/Or.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/Or.cs
similarity index 83%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/Or.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/Or.cs
index 2720ca71..97649b4f 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/Or.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/Or.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void Or_OtherFactoryIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.Or(null!));
-        Assert.AreEqual("otherFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactory", ex!.ParamName);
     }
 
     [Test]
@@ -23,7 +22,7 @@ public void Or_SourceIsFirst_ExpectSource()
         var other = TaggedUnion<object, StructType>.Second(SomeTextStructType);
 
         var actual = source.Or(() => other);
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -33,7 +32,7 @@ public void Or_SourceIsSecond_ExpectSource()
         var other = TaggedUnion<object, RefType>.Second(PlusFifteenIdRefType);
 
         var actual = source.Or(() => other);
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -43,6 +42,6 @@ public void Or_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<object, StructType>.First(new object());
 
         var actual = source.Or(() => other);
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrAsync.cs
similarity index 85%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrAsync.cs
index 72654968..ab75790e 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -14,7 +13,7 @@ public void OrAsync_OtherFactoryAsyncIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.ThrowsAsync<ArgumentNullException>(async () => _ = await source.OrAsync(null!));
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public async Task OrAsync_SourceIsFirst_ExpectSource()
         var other = TaggedUnion<RefType?, StructType>.First(ZeroIdRefType);
 
         var actual = await source.OrAsync(() => Task.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public async Task OrAsync_SourceIsSecond_ExpectSource()
         var other = default(TaggedUnion<object, StructType>);
 
         var actual = await source.OrAsync(() => Task.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -44,6 +43,6 @@ public async Task OrAsync_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<int, RefType>.Second(new RefType());
 
         var actual = await source.OrAsync(() => Task.FromResult(other));
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrValueAsync.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrValueAsync.cs
similarity index 85%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrValueAsync.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrValueAsync.cs
index f1964507..a3fc2ffd 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/Or/OrValueAsync.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/Or/OrValueAsync.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Threading.Tasks;
 using static PrimeFuncPack.UnitTest.TestData;
@@ -14,7 +13,7 @@ public void OrValueAsync_OtherFactoryAsyncIsNull_ExpectArgumentNullException(
         TaggedUnion<RefType, StructType> source)
     {
         var ex = Assert.ThrowsAsync<ArgumentNullException>(async () => _ = await source.OrValueAsync(null!));
-        Assert.AreEqual("otherFactoryAsync", ex!.ParamName);
+        ClassicAssert.AreEqual("otherFactoryAsync", ex!.ParamName);
     }
 
     [Test]
@@ -24,7 +23,7 @@ public async Task OrValueAsync_SourceIsFirst_ExpectSource()
         var other = default(TaggedUnion<StructType, DateTime>);
 
         var actual = await source.OrValueAsync(() => ValueTask.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -34,7 +33,7 @@ public async Task OrValueAsync_SourceIsSecond_ExpectSource()
         var other = TaggedUnion<object, StructType>.Second(SomeTextStructType);
 
         var actual = await source.OrValueAsync(() => ValueTask.FromResult(other));
-        Assert.AreEqual(source, actual);
+        ClassicAssert.AreEqual(source, actual);
     }
 
     [Test]
@@ -44,6 +43,6 @@ public async Task OrValueAsync_SourceIsDefault_ExpectOther()
         var other = TaggedUnion<RefType, object>.First(MinusFifteenIdRefType);
 
         var actual = await source.OrValueAsync(() => ValueTask.FromResult(other));
-        Assert.AreEqual(other, actual);
+        ClassicAssert.AreEqual(other, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs
similarity index 80%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs
index f7733994..71712b32 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.ExceptionFactory.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void FirstOrThrowWithFactory_ExceptionFactoryIsNull_ExpectArgumentNullExc
         var source = TaggedUnion<StructType, RefType>.First(SomeTextStructType);
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.FirstOrThrow(null!));
-        Assert.AreEqual("exceptionFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("exceptionFactory", ex!.ParamName);
     }
 
     [Test]
@@ -25,7 +24,7 @@ public void FirstOrThrowWithFactory_SourceIsFirst_ExpectSourceValue()
         var resultException = new SomeException();
 
         var actual = source.FirstOrThrow(() => resultException);
-        Assert.AreEqual(sourceValue, actual);
+        ClassicAssert.AreEqual(sourceValue, actual);
     }
 
     [Test]
@@ -34,10 +33,10 @@ public void FirstOrThrowWithFactory_SourceIsSecond_ExpectCreatedException()
         var source = TaggedUnion<StructType, object?>.Second(new object());
         var resultException = new SomeException();
 
-        var actualExcepption = Assert.Throws<SomeException>(
+        var actualException = Assert.Throws<SomeException>(
             () => _ = source.FirstOrThrow(() => resultException));
 
-        Assert.AreSame(resultException, actualExcepption);
+        ClassicAssert.AreSame(resultException, actualException);
     }
 
     [Test]
@@ -49,6 +48,6 @@ public void FirstOrThrowWithFactory_SourceIsDefault_ExpectInvalidOperationExcept
         var actualException = Assert.Throws<SomeException>(
             () => _ = source.FirstOrThrow(() => resultException));
 
-        Assert.AreSame(resultException, actualException);
+        ClassicAssert.AreSame(resultException, actualException);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.cs
similarity index 91%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.cs
index 3bce7084..158a3579 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/FirstOrThrow.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/FirstOrThrow.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -15,7 +14,7 @@ public void FirstOrThrow_SourceIsFirst_ExpectSourceValue(
         var source = TaggedUnion<object?, StructType>.First(sourceValue);
 
         var actual = source.FirstOrThrow();
-        Assert.AreEqual(sourceValue, actual);
+        ClassicAssert.AreEqual(sourceValue, actual);
     }
 
     [Test]
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs
similarity index 84%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs
index 6b5e5ecd..f631feab 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.ExceptionFactory.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -13,7 +12,7 @@ public void SecondOrThrowWithFactory_ExceptionFactoryIsNull_ExpectArgumentNullEx
         var source = TaggedUnion<StructType, RefType>.Second(MinusFifteenIdRefType);
 
         var ex = Assert.Throws<ArgumentNullException>(() => _ = source.SecondOrThrow(null!));
-        Assert.AreEqual("exceptionFactory", ex!.ParamName);
+        ClassicAssert.AreEqual("exceptionFactory", ex!.ParamName);
     }
 
     [Test]
@@ -25,7 +24,7 @@ public void SecondOrThrowWithFactory_SourceIsSecond_ExpectSourceValue(
         var resultException = new SomeException();
 
         var actual = source.SecondOrThrow(() => resultException);
-        Assert.AreEqual(sourceValue, actual);
+        ClassicAssert.AreEqual(sourceValue, actual);
     }
 
     [Test]
@@ -37,7 +36,7 @@ public void SecondOrThrowWithFactory_SourceIsFirst_ExpectCreatedException()
         var actualExcepption = Assert.Throws<SomeException>(
             () => _ = source.SecondOrThrow(() => resultException));
 
-        Assert.AreSame(resultException, actualExcepption);
+        ClassicAssert.AreSame(resultException, actualExcepption);
     }
 
     [Test]
@@ -49,6 +48,6 @@ public void SecondOrThrowWithFactory_SourceIsDefault_ExpectInvalidOperationExcep
         var actualExcepption = Assert.Throws<SomeException>(
             () => _ = source.SecondOrThrow(() => resultException));
 
-        Assert.AreSame(resultException, actualExcepption);
+        ClassicAssert.AreSame(resultException, actualExcepption);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.cs
similarity index 90%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.cs
index 355bd505..b6ba57e2 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/OrThrow/SecondOrThrow.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/OrThrow/SecondOrThrow.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using static PrimeFuncPack.UnitTest.TestData;
 
@@ -14,7 +13,7 @@ public void SecondOrThrow_SourceIsSecond_ExpectSourceValue()
         TaggedUnion<StructType?, RefType> source = sourceValue;
 
         var actual = source.SecondOrThrow();
-        Assert.AreEqual(sourceValue, actual);
+        ClassicAssert.AreEqual(sourceValue, actual);
     }
 
     [Test]
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/TaggedUnionTest.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/TaggedUnionTest.cs
similarity index 71%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/TaggedUnionTest.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/TaggedUnionTest.cs
index 036fa11a..d4029d35 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/TaggedUnionTest.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/TaggedUnionTest.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using System;
+using System;
 
 namespace PrimeFuncPack.Core.Tests;
 
@@ -14,7 +13,7 @@ private static void AssertContains(
         string? actual,
         StringComparison comparison = StringComparison.Ordinal)
     {
-        Assert.NotNull(actual);
-        Assert.True(actual!.Contains(expectedSubstring, comparison));
+        ClassicAssert.NotNull(actual);
+        ClassicAssert.True(actual!.Contains(expectedSubstring, comparison));
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.First.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.First.cs
similarity index 92%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.First.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.First.cs
index 6b421f05..540a5d74 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.First.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.First.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -22,7 +21,7 @@ public void ToString_SourceIsFirstAndValueIsNull()
             typeof(StructType).Name,
             string.Empty);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -39,7 +38,7 @@ public void ToString_SourceIsFirstAndValueToStringReturnsNull()
             typeof(RefType).Name,
             string.Empty);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -66,7 +65,7 @@ public void ToString_SourceIsFirst_ValueToString_Common(
             typeof(RefType).Name,
             resultOfValueToString);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -95,7 +94,7 @@ public void ToString_SourceIsFirst_Common(
             typeof(RefType).Name,
             sourceValue);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -113,7 +112,7 @@ public void ToString_SourceIsFirst_DecimalPoint(
             typeof(RefType).Name,
             expectedDecimalSubstr);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     private static IEnumerable<object[]> ToString_SourceIsFirst_DecimalPoint_TestCaseSource()
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.None.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.None.cs
similarity index 82%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.None.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.None.cs
index fe8aff9d..b63a3440 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.None.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.None.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Globalization;
 
@@ -20,6 +19,6 @@ public void ToString_SourceIsNone()
             typeof(StructType).Name,
             typeof(RefType).Name);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 }
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.Second.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.Second.cs
similarity index 92%
rename from src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.Second.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.Second.cs
index a444b279..ff0b0d78 100644
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Test/ToString/ToString.Second.cs
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Test/ToString/ToString.Second.cs
@@ -1,5 +1,4 @@
-using NUnit.Framework;
-using PrimeFuncPack.UnitTest;
+using PrimeFuncPack.UnitTest;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -22,7 +21,7 @@ public void ToString_SourceIsSecondAndValueIsNull()
             typeof(StructType?).Name,
             string.Empty);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -39,7 +38,7 @@ public void ToString_SourceIsSecondAndValueToStringReturnsNull()
             typeof(StubToStringType).Name,
             string.Empty);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -66,7 +65,7 @@ public void ToString_SourceIsSecond_ValueToString_Common(
             typeof(StubToStringType).Name,
             resultOfValueToString);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -95,7 +94,7 @@ public void ToString_SourceIsSecond_Common(
             typeof(object).Name,
             sourceValue);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     [Test]
@@ -113,7 +112,7 @@ public void ToString_SourceIsSecond_DecimalPoint(
             typeof(object).Name,
             expectedDecimalSubstr);
 
-        Assert.AreEqual(expected, actual);
+        ClassicAssert.AreEqual(expected, actual);
     }
 
     private static IEnumerable<object[]> ToString_SourceIsSecond_DecimalPoint_TestCaseSource()
diff --git a/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Tests.Old.csproj b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Tests.Old.csproj
new file mode 100644
index 00000000..161f96d8
--- /dev/null
+++ b/src/core-taggeds-union/TaggedUnion.Tests.Old/TaggedUnion.Tests.Old.csproj
@@ -0,0 +1,38 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <LangVersion>latest</LangVersion>
+    <ImplicitUsings>disable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <InvariantGlobalization>true</InvariantGlobalization>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+    <Authors>Andrei Sergeev, Pavel Moskovoy</Authors>
+    <Copyright>Copyright © 2020-2024 Andrei Sergeev, Pavel Moskovoy</Copyright>
+    <RootNamespace>PrimeFuncPack.Core.Tests</RootNamespace>
+    <AssemblyName>PrimeFuncPack.Core.TaggedUnion.Tests.Old</AssemblyName>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <NoWarn>CS0618;NUnit2001;NUnit2004;NUnit2005;NUnit2006;NUnit2015;NUnit2017;NUnit2018</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
+    <PackageReference Include="NUnit" Version="4.0.1" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
+    <PackageReference Include="NUnit.Analyzers" Version="4.0.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="PrimeFuncPack.UnitTest.Data" Version="3.1.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\TaggedUnion\TaggedUnion.csproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TestData/SomeException.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/SomeException.cs
similarity index 100%
rename from src/core-taggeds-union/TaggedUnion.Tests/TestData/SomeException.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/SomeException.cs
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TestData/StubToStringType.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/StubToStringType.cs
similarity index 100%
rename from src/core-taggeds-union/TaggedUnion.Tests/TestData/StubToStringType.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/StubToStringType.cs
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TestData/TestDataSource.cs b/src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/TestDataSource.cs
similarity index 100%
rename from src/core-taggeds-union/TaggedUnion.Tests/TestData/TestDataSource.cs
rename to src/core-taggeds-union/TaggedUnion.Tests.Old/TestData/TestDataSource.cs
diff --git a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Tests.csproj b/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Tests.csproj
deleted file mode 100644
index 533a5a83..00000000
--- a/src/core-taggeds-union/TaggedUnion.Tests/TaggedUnion.Tests.csproj
+++ /dev/null
@@ -1,27 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
-    <ImplicitUsings>disable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <InvariantGlobalization>true</InvariantGlobalization>
-    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-    <IsPackable>false</IsPackable>
-    <Authors>Andrei Sergeev, Pavel Moskovoy</Authors>
-    <Copyright>Copyright © 2020-2023 Andrei Sergeev, Pavel Moskovoy</Copyright>
-    <RootNamespace>PrimeFuncPack.Core.Tests</RootNamespace>
-    <AssemblyName>PrimeFuncPack.Core.TaggedUnion.Tests</AssemblyName>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <PackageReference Include="NUnit" Version="3.13.3" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.4.2" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
-    <PackageReference Include="PrimeFuncPack.UnitTest.Data" Version="3.1.0" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <ProjectReference Include="..\TaggedUnion\TaggedUnion.csproj" />
-  </ItemGroup>
-
-</Project>
diff --git a/src/core-taggeds-union/TaggedUnion/TaggedUnion.T/TaggedUnion.T.cs b/src/core-taggeds-union/TaggedUnion/TaggedUnion.T/TaggedUnion.T.cs
index 1ea5cc9d..e0ae7ea1 100644
--- a/src/core-taggeds-union/TaggedUnion/TaggedUnion.T/TaggedUnion.T.cs
+++ b/src/core-taggeds-union/TaggedUnion/TaggedUnion.T/TaggedUnion.T.cs
@@ -1,5 +1,6 @@
 namespace System;
 
+[Obsolete("TaggedUnion is obsolete and will be removed in Taggeds v3.0.", error: false)]
 public readonly partial struct TaggedUnion<TFirst, TSecond> : IEquatable<TaggedUnion<TFirst, TSecond>>
 {
     private readonly Tag tag;
diff --git a/src/core-taggeds-union/TaggedUnion/TaggedUnion.csproj b/src/core-taggeds-union/TaggedUnion/TaggedUnion.csproj
index 678ce4f8..6e328b79 100644
--- a/src/core-taggeds-union/TaggedUnion/TaggedUnion.csproj
+++ b/src/core-taggeds-union/TaggedUnion/TaggedUnion.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net7.0;net8.0</TargetFrameworks>
+    <LangVersion>latest</LangVersion>
     <ImplicitUsings>disable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <InvariantGlobalization>true</InvariantGlobalization>
@@ -13,11 +14,11 @@
     <RepositoryUrl>https://github.com/pfpack/pfpack-core-taggeds</RepositoryUrl>
     <Company>pfpack</Company>
     <Authors>Andrei Sergeev, Pavel Moskovoy</Authors>
-    <Copyright>Copyright © 2020-2023 Andrei Sergeev, Pavel Moskovoy</Copyright>
+    <Copyright>Copyright © 2020-2024 Andrei Sergeev, Pavel Moskovoy</Copyright>
     <Description>PrimeFuncPack Core.TaggedUnion is a core library for .NET consisting of Tagged Union targeted for use in functional programming.</Description>
     <RootNamespace>System</RootNamespace>
     <AssemblyName>PrimeFuncPack.Core.TaggedUnion</AssemblyName>
-    <Version>2.1.0-preview.2</Version>
+    <Version>2.1.0-preview.3</Version>
   </PropertyGroup>
 
   <ItemGroup>
@@ -32,7 +33,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="PrimeFuncPack.Core.Unit" Version="2.2.0" />
+    <PackageReference Include="PrimeFuncPack.Core.Unit" Version="2.2.1" />
   </ItemGroup>
 
 </Project>
diff --git a/src/core-taggeds-union/TaggedUnion/TaggedUnion/TaggedUnion.cs b/src/core-taggeds-union/TaggedUnion/TaggedUnion/TaggedUnion.cs
index 8e311e5a..d5097094 100644
--- a/src/core-taggeds-union/TaggedUnion/TaggedUnion/TaggedUnion.cs
+++ b/src/core-taggeds-union/TaggedUnion/TaggedUnion/TaggedUnion.cs
@@ -1,5 +1,6 @@
 namespace System;
 
+[Obsolete("TaggedUnion is obsolete and will be removed in Taggeds v3.0.", error: false)]
 public static partial class TaggedUnion
 {
 }
diff --git a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Optional.ToTaggedUnion.cs b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Optional.ToTaggedUnion.cs
similarity index 96%
rename from src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Optional.ToTaggedUnion.cs
rename to src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Optional.ToTaggedUnion.cs
index 76f0bbe2..5f2bed61 100644
--- a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Optional.ToTaggedUnion.cs
+++ b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Optional.ToTaggedUnion.cs
@@ -5,6 +5,7 @@ namespace PrimeFuncPack.Core.Tests;
 
 partial class TaggedsExtensionsTests
 {
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.ObjectNullableTestSource))]
     public void Optional_ToTaggedUnion_OptionalIsPresent_ExpectActualIsFirst(
@@ -17,6 +18,7 @@ public void Optional_ToTaggedUnion_OptionalIsPresent_ExpectActualIsFirst(
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void Optional_ToTaggedUnion_OptionalIsAbsent_ExpectActualIsSecond()
     {
diff --git a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Result.ToTaggedUnion.cs b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Result.ToTaggedUnion.cs
similarity index 97%
rename from src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Result.ToTaggedUnion.cs
rename to src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Result.ToTaggedUnion.cs
index 08a55128..0d11f8af 100644
--- a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Result.ToTaggedUnion.cs
+++ b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.Result.ToTaggedUnion.cs
@@ -6,6 +6,7 @@ namespace PrimeFuncPack.Core.Tests;
 
 partial class TaggedUnionResultExtensions
 {
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.FailureDefaultTestSource))]
     public void Result_ToTaggedUnion_SourceResultIsDefault_ExpectUnionSecondOfDefaultValue(
@@ -17,6 +18,7 @@ public void Result_ToTaggedUnion_SourceResultIsDefault_ExpectUnionSecondOfDefaul
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.FailureSomeTextStructTypeTestSource))]
     public void Result_ToTaggedUnion_SourceResultIsFailure_ExpectUnionSecondOfSourceFailureValue(
@@ -28,6 +30,7 @@ public void Result_ToTaggedUnion_SourceResultIsFailure_ExpectUnionSecondOfSource
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.SuccessNullTestSource))]
     public void Result_ToTaggedUnion_SourceResultIsSuccessAndSourceValueIsNull_ExpectUnionFirstOfNullValue(
@@ -39,6 +42,7 @@ public void Result_ToTaggedUnion_SourceResultIsSuccessAndSourceValueIsNull_Expec
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.SuccessPlusFifteenIdRefTypeTestSource))]
     public void Result_ToTaggedUnion_SourceResultIsSuccessAndSourceValueIsNotNull_ExpectUnionFirstOfSourceSuccessValue(
diff --git a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToOptional.cs b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToOptional.cs
similarity index 96%
rename from src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToOptional.cs
rename to src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToOptional.cs
index f520f55e..8a832eef 100644
--- a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToOptional.cs
+++ b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToOptional.cs
@@ -5,6 +5,7 @@ namespace PrimeFuncPack.Core.Tests;
 
 partial class TaggedsExtensionsTests
 {
+    [Obsolete]
     [Test]
     [TestCaseSource(typeof(TestDataSource), nameof(TestDataSource.ObjectNullableTestSource))]
     public void TaggedUnion_ToOptional_UnionIsFirst_ExpectPresent(
@@ -17,6 +18,7 @@ public void TaggedUnion_ToOptional_UnionIsFirst_ExpectPresent(
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToOptional_UnionIsDefault_ExpectAbsent()
     {
@@ -27,6 +29,7 @@ public void TaggedUnion_ToOptional_UnionIsDefault_ExpectAbsent()
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToOptional_UnionIsSecond_ExpectAbsent()
     {
diff --git a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToResult.cs b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToResult.cs
similarity index 96%
rename from src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToResult.cs
rename to src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToResult.cs
index c7ef2071..cbdb6247 100644
--- a/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/TaggedUnion.ToResult.cs
+++ b/src/core-taggeds/Taggeds.Tests.Old/TaggedsExtensionsTests/Obsolete.TaggedUnion.ToResult.cs
@@ -6,6 +6,7 @@ namespace PrimeFuncPack.Core.Tests;
 
 partial class TaggedUnionResultExtensions
 {
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToResult_SourceUnionIsDefault_ExpectDefaultResult()
     {
@@ -17,6 +18,7 @@ public void TaggedUnion_ToResult_SourceUnionIsDefault_ExpectDefaultResult()
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToResult_SourceUnionIsSecond_ExpectFailureResult()
     {
@@ -29,6 +31,7 @@ public void TaggedUnion_ToResult_SourceUnionIsSecond_ExpectFailureResult()
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToResult_SourceUnionIsFirstAndSourceValueIsNull_ExpectSuccessResultOfNullValue()
     {
@@ -40,6 +43,7 @@ public void TaggedUnion_ToResult_SourceUnionIsFirstAndSourceValueIsNull_ExpectSu
         Assert.That(actual, Is.EqualTo(expected));
     }
 
+    [Obsolete]
     [Test]
     public void TaggedUnion_ToResult_SourceUnionIsFirstAndSourceValueIsNotNull_ExpectSuccessResultOfSourceValue()
     {
diff --git a/src/core-taggeds/Taggeds/Taggeds.csproj b/src/core-taggeds/Taggeds/Taggeds.csproj
index 80a8636d..b926a1b6 100644
--- a/src/core-taggeds/Taggeds/Taggeds.csproj
+++ b/src/core-taggeds/Taggeds/Taggeds.csproj
@@ -36,7 +36,7 @@
     <PackageReference Include="PrimeFuncPack.Core.Failure" Version="2.2.0" />
     <PackageReference Include="PrimeFuncPack.Core.Optional" Version="2.2.0-preview.3" />
     <PackageReference Include="PrimeFuncPack.Core.Result" Version="2.1.0-preview.4" />
-    <PackageReference Include="PrimeFuncPack.Core.TaggedUnion" Version="2.1.0-preview.2" />
+    <PackageReference Include="PrimeFuncPack.Core.TaggedUnion" Version="2.1.0-preview.3" />
     <PackageReference Include="PrimeFuncPack.Core.Unit" Version="2.2.1" />
   </ItemGroup>
 
diff --git a/src/core-taggeds/Taggeds/TaggedsExtensions/Optional.ToTaggedUnion.cs b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Optional.ToTaggedUnion.cs
similarity index 71%
rename from src/core-taggeds/Taggeds/TaggedsExtensions/Optional.ToTaggedUnion.cs
rename to src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Optional.ToTaggedUnion.cs
index 48de4292..09ff9522 100644
--- a/src/core-taggeds/Taggeds/TaggedsExtensions/Optional.ToTaggedUnion.cs
+++ b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Optional.ToTaggedUnion.cs
@@ -2,6 +2,7 @@
 
 partial class TaggedsExtensions
 {
+    [Obsolete("TaggedUnion and this method are obsolete and will be removed in Taggeds v3.0.", error: false)]
     public static TaggedUnion<T, Unit> ToTaggedUnion<T>(this Optional<T> optional)
         =>
         optional.Fold<TaggedUnion<T, Unit>>(
diff --git a/src/core-taggeds/Taggeds/TaggedsExtensions/Result.ToTaggedUnion.cs b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Result.ToTaggedUnion.cs
similarity index 76%
rename from src/core-taggeds/Taggeds/TaggedsExtensions/Result.ToTaggedUnion.cs
rename to src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Result.ToTaggedUnion.cs
index b5671c21..68892a72 100644
--- a/src/core-taggeds/Taggeds/TaggedsExtensions/Result.ToTaggedUnion.cs
+++ b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.Result.ToTaggedUnion.cs
@@ -2,6 +2,7 @@
 
 partial class TaggedsExtensions
 {
+    [Obsolete("TaggedUnion and this method are obsolete and will be removed in Taggeds v3.0.", error: false)]
     public static TaggedUnion<TSuccess, TFailure> ToTaggedUnion<TSuccess, TFailure>(
         this Result<TSuccess, TFailure> result)
         where TFailure : struct
diff --git a/src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToOptional.cs b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToOptional.cs
similarity index 69%
rename from src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToOptional.cs
rename to src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToOptional.cs
index da736440..9881983b 100644
--- a/src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToOptional.cs
+++ b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToOptional.cs
@@ -2,6 +2,7 @@
 
 partial class TaggedsExtensions
 {
+    [Obsolete("TaggedUnion and this method are obsolete and will be removed in Taggeds v3.0.", error: false)]
     public static Optional<T> ToOptional<T>(this TaggedUnion<T, Unit> union)
         =>
         union.Fold<Optional<T>>(
diff --git a/src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToResult.cs b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToResult.cs
similarity index 76%
rename from src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToResult.cs
rename to src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToResult.cs
index d2754e83..3a7bf604 100644
--- a/src/core-taggeds/Taggeds/TaggedsExtensions/TaggedUnion.ToResult.cs
+++ b/src/core-taggeds/Taggeds/TaggedsExtensions/Obsolete.TaggedUnion.ToResult.cs
@@ -2,6 +2,7 @@
 
 partial class TaggedsExtensions
 {
+    [Obsolete("TaggedUnion and this method are obsolete and will be removed in Taggeds v3.0.", error: false)]
     public static Result<TSuccess, TFailure> ToResult<TSuccess, TFailure>(
         this TaggedUnion<TSuccess, TFailure> union)
         where TFailure : struct