public virtual void DoStuff3()
{
Assert.IsNotNull(this._foo, this._foo.Value, "Attribute has been injected");
ListQuery <Attribute> attrs = this._attributeHolder.AllAttributes[typeof(FooAttribute)];
Assert.IsTrue(attrs.Cast <FooAttribute>().Any(attr => attr.Value.Equals(THIRD_TEST_STRING)), "Attribute holder must contain attribute declared in composite type.");
Assert.IsTrue(attrs.Cast <FooAttribute>().Any(attr => attr.Value.Equals(THIRD_TEST_STRING_MIXIN)), "Attribute holder must contain attribute declared in mixin type.");
Assert.AreEqual(DO_STUFF_3_METHOD, this._method, "Correct Method has been injected.");
this.next.DoStuff3();
}