IComparable in Vector2 and unit tests for it

Hypercube.Math/Vectors/Vector2.cs

@@ -5,7 +5,7 @@
 namespace Hypercube.Math.Vectors;
 
 [StructLayout(LayoutKind.Sequential)]
-public readonly partial struct Vector2 : IEquatable<Vector2>
+public readonly partial struct Vector2 : IEquatable<Vector2>, IComparable<Vector2>
 {
     public static readonly Vector2 NaN = new(float.NaN, float.NaN);
     public static readonly Vector2 Zero = new(0, 0);
@@ -262,4 +262,16 @@ public static float Cross(Vector2 a, Vector2 b)
     {
         return a.X * b.Y - a.Y * b.X;
     }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public int CompareTo(Vector2 other)
+    {
+        return LengthSquared.CompareTo(other.LengthSquared);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public int CompareTo(Vector2 other, Func<Vector2, double> selector)
+    {
+        return selector(this).CompareTo(selector(other));
+    }
 }

Hypercube.UnitTests/Math/CompareToTest.cs

@@ -0,0 +1,96 @@
+using System;
+using Hypercube.Math.Vectors;
+using NUnit.Framework;
+
+namespace Hypercube.UnitTests.Math;
+
+[TestFixture]
+public sealed class CompareToTest
+{
+    [Test]
+    public void CompareTo_LengthComparison_ReturnsExpectedResult()
+    {
+        // Arrange
+        var vector1 = new Vector2(3, 4); // Length = 5
+        var vector2 = new Vector2(6, 8); // Length = 10
+
+        // Act
+        var result = vector1.CompareTo(vector2);
+
+        // Assert
+        Assert.Less(result, 0);
+    }
+
+    [Test]
+    public void CompareTo_XComponentComparison_ReturnsExpectedResult()
+    {
+        // Arrange
+        var vector1 = new Vector2(3, 4);
+        var vector2 = new Vector2(6, 4);
+
+        // Act
+        var result = vector1.CompareTo(vector2, v => v.X);
+
+        // Assert
+        Assert.Less(result, 0); // Expecting vector1 to be "less than" vector2 based on X component
+    }
+
+    [Test]
+    public void CompareTo_YComponentComparison_ReturnsExpectedResult()
+    {
+        // Arrange
+        var vector1 = new Vector2(3, 4);
+        var vector2 = new Vector2(3, 2);
+
+        // Act
+        var result = vector1.CompareTo(vector2, v => v.Y);
+
+        // Assert
+        Assert.Greater(result, 0); // Expecting vector1 to be "greater than" vector2 based on Y component
+    }
+
+    [Test]
+    public void CompareTo_AngleComparison_ReturnsExpectedResult()
+    {
+        // Arrange
+        var vector1 = new Vector2(0, 1); // Angle = π/2 (90 degrees)
+        var vector2 = new Vector2(1, 0); // Angle = 0 degrees
+
+        // Act
+        var result = vector1.CompareTo(vector2, v => v.Angle);
+
+        // Assert
+        Assert.Greater(result, 0); // Expecting vector1 to be "greater than" vector2 based on Angle
+    }
+
+    [Test]
+    public void CompareTo_SameVectors_ReturnsZero()
+    {
+        // Arrange
+        var vector1 = new Vector2(3, 4);
+        var vector2 = new Vector2(3, 4);
+
+        // Act & Assert
+        Assert.AreEqual(0, vector1.CompareTo(vector2));
+        Assert.AreEqual(0, vector1.CompareTo(vector2, v => v.X));
+        Assert.AreEqual(0, vector1.CompareTo(vector2, v => v.Y));
+        Assert.AreEqual(0, vector1.CompareTo(vector2, v => v.Angle));
+    }
+
+    [Test]
+    public void CompareTo_DifferentComparisons_ReturnDifferentResults()
+    {
+        // Arrange
+        var vector1 = new Vector2(1, 2);
+        var vector2 = new Vector2(2, 1);
+
+        // Act
+        var lengthComparison = vector1.CompareTo(vector2);
+        var xComponentComparison = vector1.CompareTo(vector2, v => v.X);
+        var yComponentComparison = vector1.CompareTo(vector2, v => v.Y);
+
+        // Assert
+        Assert.AreNotEqual(lengthComparison, xComponentComparison);
+        Assert.AreNotEqual(xComponentComparison, yComponentComparison);
+    }
+}