Question

I am playing around with MbUnit and Rhino Mocks and made a simple test. It may be poorly designed code, but I am more focused on just seeing if I can get the test to pass. Basically, When the engine light of a car is on, the car should an oil change. Here is code:

public interface ICar
{
    bool EngineLight { get; set; }
    void GetOilChange();
    bool CheckEngineLight(ICar car);
}

public class Car : ICar
{
    public bool EngineLight { get; set; }

    public void GetOilChange()
    {
    }

    public bool CheckEngineLight(ICar car)
    {
        if (car.EngineLight)
            GetOilChange();
            return true;

        return false;
    } 
}

[TestFixture]
public class CarTests
{
[Test]
    public void WhenEngineLightIsOnGetOilChange()
    {
        var carMock = MockRepository.GenerateMock<ICar>();
        carMock.Stub(x => x.EngineLight).Return(true);

        Assert.AreEqual(true, new Car().CheckEngineLight(carMock)); //This passes

        carMock.AssertWasCalled(x => x.GetOilChange()); //This fails
    }
 }

Answer 1

First off, this code has a bug. Add in the {} around the IF:

public bool CheckEngineLight(ICar car)
    {
        if (car.EngineLight)
        {
            car.GetOilChange();
            return true;
        }

        return false;
    } 

The reason it fails is because you are calling new Car().CheckEngineLight … and the new Car() is calling GetOilChange … the carMock is not calling GetOilChange. Change the code to car.GetOilChange() (see it in the code above).

The fact that you are passing a Car object into a method on the Car Object is very confusing. Why not change the code to this:

public class Car : ICar
{
    public bool EngineLight { get; set; }

    public void GetOilChange()
    {
    }

    public bool CheckEngineLight()
    {
        if (EngineLight)
        {
            GetOilChange();
            return true;
        }

        return false;
    } 
}

Change your test to:

[Test]
    public void WhenEngineLightIsOnGetOilChange()
    {
        var carMock = MockRepository.GenerateMock<ICar>();
        carMock.Stub(x => x.EngineLight).Return(true);

        Assert.AreEqual(true, carMock.CheckEngineLight()); 

        carMock.AssertWasCalled(x => x.GetOilChange()); 
    }
 }