Question

Is there a way to unit test raising an event with moq if an event that is used in an interface implementation does not appear in the interface you are mocking?

Note: My interface doesn’t have anything to do with my UI and my events are just used for UI notifications, so I wanted to decouple that behavior from the actual interface as the repository is in a separate library from the client/UI.

For example:

    [Test]
    public void TestRaiseBarProcessed()
    {
        ManualResetEvent barProcessedEvent = new ManualResetEvent(false);
        bool called = false;

        //Arrange
        Mock<IFooRepository> mockFooRepository = new Mock<IFooRepository>();

        mockSourceRepository
            .Setup(a => a.SearchForBar(barsToFind))
            .Returns(barsFound)
            .Raises(
                a => a.BarProcessed += null, 
                new BarFoundEventArgs(It.IsAny<string>()));

        IList<IFooRepository> mockFooRepositories = 
            new List<IFooRepository>();

        mockFooRepositories.Add(mockFooRepository.Object);

        FooBar fooBar = new FooBar(mockFooRepositories, FooList);

        fooBar.CurrentBarBeingProcessedInfo += (sender, e) =>
            {
                barProcessedEvent.Set();
                called = true;
            };

        //Act
        fooBar.CallFooRepositoryMethod();

        barProcessedEvent.WaitOne(25, false);

        //Assert
        mockFooRepository.Verify(
            a => a.SearchForBar(barsToFind),
            Times.Once());

        Assert.AreEqual(true, called);
    }

Let me know if any of this needs more clarification.

Answer 1

Did you consider having that UI-only event defined in another interface and implementing both of them? If so, you could then use Moq’s multiple-interface mocks:

var fooRepositoryMock = new Mock<IFooRepository>();
var barUiEventMock = fooRepositoryMock.As<IBarUiEvent>();
bool wasCalled = false;
barUiEventMock.Object.BarProcessed += (s, e) => wasCalled = true;

fooRepositoryMock
    .Setup(m => m.SearchForBars(barsToFind))
    .Returns(barsFound)
    .Raises(
        foo => barUiEventMock.Object.BarProcessed += null,
        new BarFoundEventArgs("")
    );

// ...

Assert.That(wasCalled, Is.True);

Call to SearchForBars will cause BarProcessed event to be raised with whatever arguments you pass.