Mocking calls to contained private classes

Hi,

I am trying to mock calls to a private member object. The code below is a made up example I created to reproduce the problem. I am testing Car.Start() and want to mock calls to Car.myEingine.Start() to test what happens if the method returns false instead of true.

The test code below shows 3 experiments that failed: (1) I cannot reach the private class because of its protection level, (2) using reflective mocks does not support chaining and (3) mocking the private accessor does not mock the actual class...

Any help is greatly appreciated,

Thanks,
Wael


CLASS UNDER TEST:

public class Car
{
private class Engine
{
public bool Start()
{
return true;
}
}

private Engine myEngine = new Engine();

public bool Start()
{
return myEngine.Start();
}
}



UNIT TEST CODE:

[TestMethod()]
public void StartTest()
{
MockManager.Init();
Car target = new Car();

// EXPERIMENT 1: Does not work due to protection level of Car.Engine
//Mock mock = MockManager.MockAll(typeof(TestLibrary.Car.Engine));
//

// EXPERIMENT 2: Chaining: Throws exception: No method "Engine.Start" on class Car
//Mock mock = MockManager.MockAll(typeof(TestLibrary.Car));
//mock.ExpectAndReturn("Engine.Start", (bool)false);
//

// EXPERIMENT 3: Mock the private accessor??
// Does not mock the class under test
//TestLibrary_Car_EngineAccessor pa = new TestLibrary_Car_EngineAccessor(target);
//using (RecordExpectations recorder = RecorderManager.StartRecording())
//{
// recorder.ExpectAndReturn(pa.Start(), (bool)false);
//}
//

bool expected = false; bool actual;
actual = target.Start();

Assert.AreEqual(expected, actual, "Test Failed");
MockManager.Verify();
}