Working with unit tests and making a few corrections around ContentTypes.

src/Umbraco.Tests/CodeFirst/Attributes/MixinAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Umbraco.Tests.CodeFirst.Attributes
+{
+    [AttributeUsage(AttributeTargets.Interface, AllowMultiple = false, Inherited = true)]
+    public class MixinAttribute : Attribute
+    {
+        public MixinAttribute(Type type)
+        {
+            Type = type;
+        }
+
+        /// <summary>
+        /// Gets or sets the Type of the implementing class
+        /// </summary>
+        public Type Type { get; private set; }
+    }
+}

src/Umbraco.Tests/CodeFirst/Attributes/Numeric.cs

@@ -30,8 +30,8 @@ namespace Umbraco.Tests.CodeFirst.Attributes
 
             if(string.IsNullOrEmpty(PreValue) == false)
             {
-                Conventions.CreatePrevalueForDataTypeDefinition(definition.DataTypeDefinition.Id, PreValue, 0,
-                                                                string.Empty);
+                //TODO - test inserting a prevalue when a DataTypeDefinition has been created, as its currently throwing a foreignkey constraint error.
+                Conventions.CreatePrevalueForDataTypeDefinition(definition.DataTypeDefinition.Id, PreValue, 0, string.Empty);
             }
 
             return definition;