diff --git a/ModuleManagerTests/Collections/ImmutableStackTest.cs b/ModuleManagerTests/Collections/ImmutableStackTest.cs
new file mode 100644
index 00000000..56265d45
--- /dev/null
+++ b/ModuleManagerTests/Collections/ImmutableStackTest.cs
@@ -0,0 +1,140 @@
+using System;
+using System.Linq;
+using Xunit;
+
+using ModuleManager.Collections;
+
+namespace ModuleManagerTests.Collections
+{
+    public class ImmutableStackTest
+    {
+        [Fact]
+        public void TestValue()
+        {
+            object obj = new object();
+            ImmutableStack<object> stack = new ImmutableStack<object>(obj);
+
+            Assert.Same(obj, stack.value);
+        }
+
+        [Fact]
+        public void TestIsRoot()
+        {
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(new object());
+            ImmutableStack<object> stack2 = stack1.Push(new object());
+
+            Assert.True(stack1.IsRoot);
+            Assert.False(stack2.IsRoot);
+        }
+
+        [Fact]
+        public void TestRoot()
+        {
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(new object());
+            ImmutableStack<object> stack2 = stack1.Push(new object());
+            ImmutableStack<object> stack3 = stack2.Push(new object());
+
+            Assert.Same(stack1, stack1.Root);
+            Assert.Same(stack1, stack2.Root);
+            Assert.Same(stack1, stack3.Root);
+        }
+
+        [Fact]
+        public void TestDepth()
+        {
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(new object());
+            ImmutableStack<object> stack2 = stack1.Push(new object());
+            ImmutableStack<object> stack3 = stack2.Push(new object());
+
+            Assert.Equal(1, stack1.Depth);
+            Assert.Equal(2, stack2.Depth);
+            Assert.Equal(3, stack3.Depth);
+        }
+
+        [Fact]
+        public void TestPush()
+        {
+            object obj1 = new object();
+            object obj2 = new object();
+            object obj3 = new object();
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(obj1);
+            ImmutableStack<object> stack2 = stack1.Push(obj2);
+            ImmutableStack<object> stack3 = stack2.Push(obj3);
+
+            Assert.Same(stack2, stack3.parent);
+            Assert.Same(stack1, stack2.parent);
+
+            Assert.Same(obj1, stack1.value);
+            Assert.Same(obj2, stack2.value);
+            Assert.Same(obj3, stack3.value);
+        }
+
+        [Fact]
+        public void TestPop()
+        {
+            object obj1 = new object();
+            object obj2 = new object();
+            object obj3 = new object();
+            ImmutableStack<object> stack = new ImmutableStack<object>(obj1).Push(obj2).Push(obj3);
+
+            Assert.Same(obj1, stack.Pop().Pop().value);
+            Assert.Same(obj2, stack.Pop().value);
+            Assert.Same(obj3, stack.value);
+        }
+
+        [Fact]
+        public void TestPop__Root()
+        {
+            ImmutableStack<object> stack = new ImmutableStack<object>(new object());
+
+            Assert.Throws<InvalidOperationException>(delegate
+            {
+                stack.Pop();
+            });
+        }
+
+        [Fact]
+        public void TestReplaceValue()
+        {
+            object obj1 = new object();
+            object obj2 = new object();
+            object obj3 = new object();
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(obj1);
+            ImmutableStack<object> stack2 = stack1.Push(obj2);
+
+            ImmutableStack<object> stack3 = stack2.ReplaceValue(obj3);
+
+            Assert.Same(obj3, stack3.value);
+            Assert.Same(stack1, stack3.parent);
+        }
+
+        [Fact]
+        public void TestReplaceValue__Root()
+        {
+            object obj1 = new object();
+            object obj2 = new object();
+            ImmutableStack<object> stack1 = new ImmutableStack<object>(obj1);
+
+            ImmutableStack<object> stack2 = stack1.ReplaceValue(obj2);
+
+            Assert.Same(obj2, stack2.value);
+            Assert.Null(stack2.parent);
+        }
+
+        [Fact]
+        public void TestEnumerator()
+        {
+            object obj1 = new object();
+            object obj2 = new object();
+            object obj3 = new object();
+            ImmutableStack<object> stack = new ImmutableStack<object>(obj1).Push(obj2).Push(obj3);
+
+            object[] objs = stack.ToArray();
+
+            Assert.Equal(3, objs.Length);
+            Assert.Same(obj3, objs[0]);
+            Assert.Same(obj2, objs[1]);
+            Assert.Same(obj1, objs[2]);
+        }
+    }
+}
diff --git a/ModuleManagerTests/ModuleManagerTests.csproj b/ModuleManagerTests/ModuleManagerTests.csproj
index 9cb9cba7..93c98364 100644
--- a/ModuleManagerTests/ModuleManagerTests.csproj
+++ b/ModuleManagerTests/ModuleManagerTests.csproj
@@ -46,6 +46,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Collections\ImmutableStackTest.cs" />
     <Compile Include="DummyTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>