diff --git a/Engine.Tests/BehaviourController_Tests.cs b/Engine.Tests/BehaviourController_Tests.cs
new file mode 100644
index 0000000..3fca482
--- /dev/null
+++ b/Engine.Tests/BehaviourController_Tests.cs
@@ -0,0 +1,267 @@
+using Syntriax.Engine.Core;
+using Syntriax.Engine.Core.Exceptions;
+
+namespace Engine.Tests;
+
+public class BehaviourController_Tests
+{
+    [Fact]
+    public void GetRequiredBehaviour()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        behaviourController.AddBehaviour<BehaviourX>();
+        Assert.NotNull(behaviourController.GetRequiredBehaviour<BehaviourX>());
+    }
+
+    [Fact]
+    public void GetRequiredBehaviourRaisesExceptionIfNotFound()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        Assert.Throws<BehaviourNotFoundException>(behaviourController.GetRequiredBehaviour<BehaviourX>);
+    }
+
+    [Fact]
+    public void AddSingleBehaviour()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        Assert.NotNull(behaviourController.AddBehaviour<BehaviourX>());
+        Assert.NotNull(behaviourController.GetBehaviour<BehaviourX>());
+    }
+
+    [Fact]
+    public void AddMultipleBehaviours()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        BehaviourX behaviourX = behaviourController.AddBehaviour<BehaviourX>();
+        BehaviourY behaviourY = behaviourController.AddBehaviour<BehaviourY>();
+
+        bool isXFound = false;
+        bool isYFound = false;
+
+        foreach (IBehaviour behaviour in behaviourController.GetBehaviours<IBehaviour>())
+        {
+            if (behaviour == behaviourX) isXFound = true;
+            if (behaviour == behaviourY) isYFound = true;
+        }
+
+        Assert.True(isXFound && isYFound);
+    }
+
+    [Fact]
+    public void AddThenRemoveBehaviour()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        behaviourController.AddBehaviour<BehaviourX>();
+        behaviourController.RemoveBehaviour<BehaviourX>();
+        Assert.Null(behaviourController.GetBehaviour<BehaviourX>());
+    }
+
+    [Fact]
+    public void GetOrAddBehaviourExtension()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        Assert.Null(behaviourController.GetBehaviour<BehaviourX>());
+        Assert.NotNull(behaviourController.GetOrAddBehaviour<BehaviourX>());
+    }
+
+    [Fact]
+    public void GetOrAddBehaviourExtensionFallback()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        Assert.Null(behaviourController.GetBehaviour<IBehaviour>());
+        Assert.NotNull(behaviourController.GetOrAddBehaviour<IBehaviour, BehaviourX>());
+    }
+
+    [Fact]
+    public void RemoveSpecificBehaviourViaGeneric()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        behaviourController.AddBehaviour<BehaviourX>();
+        behaviourController.AddBehaviour<BehaviourY>();
+        behaviourController.RemoveBehaviour<BehaviourY>();
+
+        Assert.NotNull(behaviourController.GetBehaviour<BehaviourX>());
+        Assert.Null(behaviourController.GetBehaviour<BehaviourY>());
+    }
+
+    [Fact]
+    public void RemoveSpecificBehaviourViaReference()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        behaviourController.AddBehaviour<BehaviourX>();
+
+        BehaviourY behaviourYFirst = behaviourController.AddBehaviour<BehaviourY>();
+        BehaviourY behaviourYSecond = behaviourController.AddBehaviour<BehaviourY>();
+
+        behaviourController.RemoveBehaviour(behaviourYFirst);
+
+        Assert.Equal(behaviourController.GetBehaviour<BehaviourY>(), behaviourYSecond);
+        Assert.NotNull(behaviourController.GetBehaviour<BehaviourX>());
+    }
+
+    [Fact]
+    public void AddBehaviourSameTypeCreatesSeparateInstances()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        BehaviourY first = behaviourController.AddBehaviour<BehaviourY>();
+        BehaviourY second = behaviourController.AddBehaviour<BehaviourY>();
+
+        Assert.NotSame(first, second);
+    }
+
+    [Fact]
+    public void BehaviourAddedEvents()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        IBehaviourController? sender = null;
+        IBehaviourController.BehaviourAddedArguments? arguments = null;
+
+        behaviourController.OnBehaviourAdded.AddListener((s, a) =>
+        {
+            sender = s;
+            arguments = a;
+        });
+
+        behaviourController.AddBehaviour<BehaviourX>();
+
+        Assert.NotNull(sender);
+        Assert.NotNull(arguments);
+    }
+
+    [Fact]
+    public void BehaviourRemovedEvents()
+    {
+        IBehaviourController behaviourController = CreateUniverseObject().BehaviourController;
+
+        IBehaviourController? sender = null;
+        IBehaviourController.BehaviourRemovedArguments? arguments = null;
+
+        behaviourController.OnBehaviourRemoved.AddListener((s, a) =>
+        {
+            sender = s;
+            arguments = a;
+        });
+
+        behaviourController.AddBehaviour<BehaviourX>();
+        behaviourController.RemoveBehaviour<BehaviourX>();
+
+        Assert.NotNull(sender);
+        Assert.NotNull(arguments);
+    }
+
+    #region Hierarchy Structure
+
+    private static IUniverseObject CreateUniverseObject()
+    {
+        UniverseObject universeObject = new();
+        BehaviourController behaviourController = new();
+
+        universeObject.Assign(new StateEnable());
+        universeObject.StateEnable.Assign(universeObject);
+
+        behaviourController.Assign(new StateEnable());
+        behaviourController.StateEnable.Assign(behaviourController);
+
+        behaviourController.Assign(universeObject);
+        universeObject.Assign(behaviourController);
+
+        universeObject.Initialize();
+        behaviourController.Initialize();
+
+        return universeObject;
+    }
+
+    public static IUniverseObject CreateParentChildScenario()
+    {
+        IUniverseObject parentUO = CreateUniverseObject().SetUniverseObject("Parent");
+        IUniverseObject middleUO = CreateUniverseObject().SetUniverseObject("Middle", parentUO);
+        IUniverseObject childUO = CreateUniverseObject().SetUniverseObject("Child", middleUO);
+
+        parentUO.BehaviourController.AddBehaviour<BehaviourY>();
+        middleUO.BehaviourController.AddBehaviour<BehaviourX>();
+        childUO.BehaviourController.AddBehaviour<BehaviourY>();
+
+        return middleUO;
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInParent()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.NotNull(universeObject.BehaviourController.GetBehaviourInParent<BehaviourY>());
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInChildren()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.NotNull(universeObject.BehaviourController.GetBehaviourInChildren<BehaviourY>());
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInChildrenOnSameObject()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.NotNull(universeObject.BehaviourController.GetBehaviourInChildren<BehaviourX>());
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInParentOnSameObject()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.NotNull(universeObject.BehaviourController.GetBehaviourInParent<BehaviourX>());
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInParentRaisesExceptionIfNotFound()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.Throws<BehaviourNotFoundException>(universeObject.BehaviourController.GetRequiredBehaviourInParent<BehaviourZ>);
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInChildrenRaisesExceptionIfNotFound()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.Throws<BehaviourNotFoundException>(universeObject.BehaviourController.GetRequiredBehaviourInChildren<BehaviourZ>);
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInChildrenOnSameObjectRaisesExceptionIfNotFound()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.Throws<BehaviourNotFoundException>(universeObject.BehaviourController.GetRequiredBehaviourInChildren<BehaviourZ>);
+    }
+
+    [Fact]
+    public void ParentChildScenarioGetBehaviourInParentOnSameObjectRaisesExceptionIfNotFound()
+    {
+        IUniverseObject universeObject = CreateParentChildScenario();
+
+        Assert.Throws<BehaviourNotFoundException>(universeObject.BehaviourController.GetRequiredBehaviourInParent<BehaviourZ>);
+    }
+
+    #endregion
+
+    private class BehaviourX : BehaviourBase;
+    private class BehaviourY : BehaviourBase;
+    private class BehaviourZ : BehaviourBase;
+}
diff --git a/Engine.Tests/UnitTest1.cs b/Engine.Tests/UnitTest1.cs
deleted file mode 100644
index bcddf8e..0000000
--- a/Engine.Tests/UnitTest1.cs
+++ /dev/null
@@ -1,10 +0,0 @@
-namespace Engine.Tests;
-
-public class UnitTest1
-{
-    [Fact]
-    public void Test1()
-    {
-
-    }
-}