Starting with composition via code first test.

src/Umbraco.Tests/CodeFirst/TestModels/Composition/Base.cs

@@ -0,0 +1,7 @@
+namespace Umbraco.Tests.CodeFirst.TestModels.Composition
+{
+    public class Base
+    {
+         
+    }
+}

src/Umbraco.Tests/CodeFirst/TestModels/Composition/Meta.cs

@@ -0,0 +1,10 @@
+namespace Umbraco.Tests.CodeFirst.TestModels.Composition
+{
+    public class Meta : IMeta
+    {
+         
+    }
+
+    public interface IMeta
+    {}
+}

src/Umbraco.Tests/CodeFirst/TestModels/Composition/News.cs

@@ -0,0 +1,10 @@
+namespace Umbraco.Tests.CodeFirst.TestModels.Composition
+{
+    /// <summary>
+    /// Deriving class is parent, interfaces are compositions
+    /// </summary>
+    public class News : Base, IMeta, ISeo
+    {
+         
+    }
+}

src/Umbraco.Tests/CodeFirst/TestModels/Composition/Seo.cs

@@ -0,0 +1,10 @@
+namespace Umbraco.Tests.CodeFirst.TestModels.Composition
+{
+    public class Seo : ISeo
+    {
+         
+    }
+
+    public interface ISeo
+    {}
+}

src/Umbraco.Tests/Umbraco.Tests.csproj

@@ -103,6 +103,10 @@
     <Compile Include="CodeFirst\Definitions\DependencyField.cs" />
     <Compile Include="CodeFirst\Definitions\PropertyDefinition.cs" />
     <Compile Include="CodeFirst\TestModels\AdvancedContentPage.cs" />
+    <Compile Include="CodeFirst\TestModels\Composition\Base.cs" />
+    <Compile Include="CodeFirst\TestModels\Composition\Meta.cs" />
+    <Compile Include="CodeFirst\TestModels\Composition\News.cs" />
+    <Compile Include="CodeFirst\TestModels\Composition\Seo.cs" />
     <Compile Include="CodeFirst\TestModels\ContentPage.cs" />
     <Compile Include="CodeFirst\TestModels\DecoratedModelPage.cs" />
     <Compile Include="CodeFirst\TestModels\Home.cs" />