a rough but workable way to "inject" contract tests into a NUnit fixture

gistfile1.cs

using NUnit.Framework;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace NUnitBehavesLike
{
    public interface IThingamabob
    {
        void Frooble();
        bool IsFroobled { get; }
    }

    public class ThingamabobContract
    {
        public IThingamabob TheThingy;

        public void is_froobled_after_a_frooble() {
            TheThingy.Frooble();
            Assert.That(TheThingy.IsFroobled);
        }
    }

    public class SatisfiesAttribute : TestCaseSourceAttribute 
    {
        class ContractSource<T>
        {
            public IEnumerable<ITestCaseData> GetContract() 
            {
                return typeof(T).GetMethods(BindingFlags.Public | BindingFlags.Instance)
                    .Where(x => x.DeclaringType != typeof(object) && x.ReturnType == typeof(void) && x.GetParameters().Length == 0)
                    .Select(x => new TestCaseData(new Action<T>(thingy => x.Invoke(thingy, null))).SetName(x.Name));
                }
        }

        public SatisfiesAttribute(Type contractType) : base(typeof(ContractSource<>).MakeGenericType(contractType), "GetContract") { }
    }

    [TestFixture]
    public class MyWidgetTests
    {
        class MyWidget : IThingamabob
        {
            public void Frooble() { }

            public bool IsFroobled {
                get { return false; }
            }
        }
        /* many important facts about my widget omitted for brevity */

        [Satisfies(typeof(ThingamabobContract))]
        public void BehavesLikeAThingamabob(Action<ThingamabobContract> check) { check(new ThingamabobContract { TheThingy = MyThingy }); }

        MyWidget MyThingy;

        [SetUp]
        public void CreateAWidget() {
            MyThingy = new MyWidget();
        }

    }
}