I was having trouble using the ExpectSet method which verifies that a property has been set, and a google search found nothing that directly answered my question.  I wanted to know how to verify that the value set is what was expected.

It turns out that you need to define a callback in which you have the assertion to verify that the property has been set to the correct value.

[TestMethod]
public void TestAppleShiner() {

    // Mock the interface being passed to the class to be tested
    var fruit = new Mock<IFruit>();

    // Define the expectation that the Colour property will be
    // set to Green
    fruit.ExpectSet(f=>f.Colour).Callback(
        setColor=>Assert.AreEqual("Green", setColor)).Verifiable();

    // Run the test
    ApplePolisher applePolisher = new ApplePolisher();
    applePolisher.Polish(fruit.Object);

    // Verify that the test passed (note .Verifiable on the ExpectSet)
    fruit.VerifyAll();
}

public interface IFruit {
    string Colour { get; set; }
}

public class ApplePolisher {
    public void Polish(IFruit fruit) {
        fruit.Colour = "Green";
    }
}

I have a class which has a method which kicks off a background thread.  This thread has an infinite loop -- for each loop it accepts a request and services the request.

I needed to test an instance of the class, for one specific incoming request.  There are two issues -- how to know when the object's background thread has finished servicing the request, and how to stop the background thread from looping back and accepting another request.

This is what I ended up doing:

[TestFixture]
public class ServerTest {

  [Test]
  public void SomeTest() {

    bool done = false;

    MockRepository mocks = new MockRepository();

    using(mocks.Record()) {

      // ... lots of 'Expects'

      // This is the final call which gets made in the background thread
      // to complete the handling of the request
      Expect.Call(someObject.LastMethod).Do((Expect.Action)delegate() {
        done = true;
        System.Threading.Thread.CurrentThread.Abort();
      });
    }
    using(mocks.Playback()) {
      Server server = new Server();
      server.Start();
      int count = 0;
      while(!done && count < 10) {
        System.Threading.Thread.Sleep(1000);
        count++;
      }
    }
  }
}

The key point is that in the test's action associated with the last method that gets invoked as part of your background thread's processing loop, you need to set a flag so that the test knows that the last method has executed, and also abort the current thread so that the background thread doesn't loop back, and consume another request.