diff --git a/tests/GameUtils.Tests/Extensions/ObjectExtensionsTests.cs b/tests/GameUtils.Tests/Extensions/ObjectExtensionsTests.cs
new file mode 100644
index 0000000..cb0f46a
--- /dev/null
+++ b/tests/GameUtils.Tests/Extensions/ObjectExtensionsTests.cs
@@ -0,0 +1,143 @@
+using System;
+using GameUtils.Extensions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace GameUtils.Tests.Extensions;
+
+[TestClass]
+public class ObjectExtensionsTests
+{
+    private struct DummyStruct
+    {
+        public int Value { get; set; }
+    }
+
+    private class DummyClass
+    {
+        public int Value { get; set; }
+    }
+
+    [TestMethod]
+    public void Mutate_Struct_ValidAction_ReturnsNewValue()
+    {
+        var initial = new DummyStruct { Value = 1 };
+        var result = initial.Mutate(s => new DummyStruct { Value = s.Value + 1 });
+
+        Assert.AreEqual(1, initial.Value);
+        Assert.AreEqual(2, result.Value);
+    }
+
+    [TestMethod]
+    public void Mutate_Struct_NullAction_ThrowsArgumentNullException()
+    {
+        var s = new DummyStruct();
+        Assert.ThrowsExactly<ArgumentNullException>(() => s.Mutate((Func<DummyStruct, DummyStruct>)null!));
+    }
+
+    [TestMethod]
+    public void Mutate_Class_ValidAction_ReturnsSameReference()
+    {
+        var initial = new DummyClass { Value = 1 };
+        var result = initial.Mutate(c => c.Value += 1);
+
+        Assert.AreSame(initial, result);
+        Assert.AreEqual(2, initial.Value);
+    }
+
+    [TestMethod]
+    public void Mutate_Class_NullAction_ThrowsArgumentNullException()
+    {
+        var c = new DummyClass();
+        Assert.ThrowsExactly<ArgumentNullException>(() => c.Mutate((Action<DummyClass>)null!));
+    }
+
+    [TestMethod]
+    public void Out_SetsOutParameterAndReturnsObject()
+    {
+        var obj = new DummyClass { Value = 5 };
+        var result = obj.Out(out var outObj);
+
+        Assert.AreSame(obj, result);
+        Assert.AreSame(obj, outObj);
+    }
+
+    [TestMethod]
+    public void Curry_0Args_ReturnsFuncResult()
+    {
+        Func<int, string> func = (x) => $"Value: {x}";
+        var curried = func.Curry(10);
+
+        Assert.AreEqual("Value: 10", curried());
+    }
+
+    [TestMethod]
+    public void Curry_0Args_NullFunc_ThrowsArgumentNullException()
+    {
+        Func<int, string>? func = null;
+        Assert.ThrowsExactly<ArgumentNullException>(() => func!.Curry(10));
+    }
+
+    [TestMethod]
+    public void Curry_1Args_ReturnsFuncResult()
+    {
+        Func<int, int, string> func = (x, y) => $"Value: {x}, {y}";
+        var curried = func.Curry(10);
+
+        Assert.AreEqual("Value: 10, 20", curried(20));
+    }
+
+    [TestMethod]
+    public void Curry_1Args_NullFunc_ThrowsArgumentNullException()
+    {
+        Func<int, int, string>? func = null;
+        Assert.ThrowsExactly<ArgumentNullException>(() => func!.Curry(10));
+    }
+
+    [TestMethod]
+    public void Curry_2Args_ReturnsFuncResult()
+    {
+        Func<int, int, int, string> func = (x, y, z) => $"Value: {x}, {y}, {z}";
+        var curried = func.Curry(10);
+
+        Assert.AreEqual("Value: 10, 20, 30", curried(20, 30));
+    }
+
+    [TestMethod]
+    public void Curry_2Args_NullFunc_ThrowsArgumentNullException()
+    {
+        Func<int, int, int, string>? func = null;
+        Assert.ThrowsExactly<ArgumentNullException>(() => func!.Curry(10));
+    }
+
+    [TestMethod]
+    public void Curry_3Args_ReturnsFuncResult()
+    {
+        Func<int, int, int, int, string> func = (x, y, z, w) => $"Value: {x}, {y}, {z}, {w}";
+        var curried = func.Curry(10);
+
+        Assert.AreEqual("Value: 10, 20, 30, 40", curried(20, 30, 40));
+    }
+
+    [TestMethod]
+    public void Curry_3Args_NullFunc_ThrowsArgumentNullException()
+    {
+        Func<int, int, int, int, string>? func = null;
+        Assert.ThrowsExactly<ArgumentNullException>(() => func!.Curry(10));
+    }
+
+    [TestMethod]
+    public void Curry_4Args_ReturnsFuncResult()
+    {
+        Func<int, int, int, int, int, string> func = (x, y, z, w, v) => $"Value: {x}, {y}, {z}, {w}, {v}";
+        var curried = func.Curry(10);
+
+        Assert.AreEqual("Value: 10, 20, 30, 40, 50", curried(20, 30, 40, 50));
+    }
+
+    [TestMethod]
+    public void Curry_4Args_NullFunc_ThrowsArgumentNullException()
+    {
+        Func<int, int, int, int, int, string>? func = null;
+        Assert.ThrowsExactly<ArgumentNullException>(() => func!.Curry(10));
+    }
+}