Additional VM tests.

NWNX.NET.Tests/src/main/Constants/VMFunctions.cs

@@ -0,0 +1,9 @@
+namespace NWNX.NET.Tests.Constants;
+
+public static class VMFunctions
+{
+  public const int SubString = 65;
+  public const int fabs = 67;
+  public const int abs = 77;
+  public const int GetModuleName = 561;
+}

NWNX.NET.Tests/src/main/Tests/VMTests.cs

@@ -1,4 +1,5 @@
 using NUnit.Framework;
+using NWNX.NET.Tests.Constants;
 
 namespace NWNX.NET.Tests
 {
@@ -8,10 +9,54 @@ public sealed class VMTests
     [Test]
     public void GetModuleNameTest()
     {
-      NWNXAPI.CallBuiltIn(561);
+      NWNXAPI.CallBuiltIn(VMFunctions.GetModuleName);
       string? modName = NWNXAPI.StackPopString();
 
       Assert.That(modName, Is.EqualTo("demo"));
     }
+
+    [Test]
+    [TestCase(1, 1)]
+    [TestCase(0, 0)]
+    [TestCase(-1, 1)]
+    [TestCase(-int.MaxValue, int.MaxValue)]
+    public void AbsTest(int value, int expectedValue)
+    {
+      NWNXAPI.StackPushInteger(value);
+      NWNXAPI.CallBuiltIn(VMFunctions.abs);
+      int result = NWNXAPI.StackPopInteger();
+
+      Assert.That(result, Is.EqualTo(expectedValue));
+    }
+
+    [Test]
+    [TestCase(1f, 1f)]
+    [TestCase(0f, 0f)]
+    [TestCase(-1f, 1f)]
+    [TestCase(-float.MaxValue, float.MaxValue)]
+    public void FAbsTest(float value, float expectedValue)
+    {
+      NWNXAPI.StackPushFloat(value);
+      NWNXAPI.CallBuiltIn(VMFunctions.fabs);
+      float result = NWNXAPI.StackPopFloat();
+
+      Assert.That(result, Is.EqualTo(expectedValue));
+    }
+
+    [Test]
+    [TestCase("example_string", 0, 7, "example")]
+    [TestCase("test_string", 5, 6, "string")]
+    [TestCase("", 0, 0, "")]
+    [TestCase(null, 0, 5, "")]
+    public void SubStringTest(string str, int start, int count, string expectedValue)
+    {
+      NWNXAPI.StackPushInteger(count);
+      NWNXAPI.StackPushInteger(start);
+      NWNXAPI.StackPushString(str);
+      NWNXAPI.CallBuiltIn(VMFunctions.SubString);
+
+      string? result = NWNXAPI.StackPopString();
+      Assert.That(result, Is.EqualTo(expectedValue));
+    }
   }
 }