http://jbazuzicode.blogspot.com/2015/02/how-i-write-contract-tests.html

ContractTests.cs

abstract class AdapterTestsBase
{
    public abstract IPort CreateSubject();

    [TestMethod]
    public void FShouldBlah()
    {
        IPort subject = CreateSubject();
        int result = subject.F();
        Assert.AreEqual(7, result);
    }

    // More tests here...
}

[TestClass]
class RealAdapterTests : AdapterTestsBase
{
    public override IPort CreateSubject()
    {
        return new RealAdapter();
    }
}

[TestClass]
class InMemoryAdapterTests : AdapterTestsBase
{
    public override IPort CreateSubject()
    {
        return new InMemoryAdapter();
    }
}