How to test method call order with Moq

At the moment I have:

    [Test]
    public void DrawDrawsAllScreensInTheReverseOrderOfTheStack() {
        // Arrange.
        var screenMockOne = new Mock<IScreen>();
        var screenMockTwo = new Mock<IScreen>();
        var screens = new List<IScreen>();
        screens.Add(screenMockOne.Object);
        screens.Add(screenMockTwo.Object);
        var stackOfScreensMock = new Mock<IScreenStack>();
        stackOfScreensMock.Setup(s => s.ToArray()).Returns(screens.ToArray());
        var screenManager = new ScreenManager(stackOfScreensMock.Object);
        // Act.
        screenManager.Draw(new Mock<GameTime>().Object);
        // Assert.
        screenMockOne.Verify(smo => smo.Draw(It.IsAny<GameTime>()), Times.Once(),
            "Draw was not called on screen mock one");
        screenMockTwo.Verify(smo => smo.Draw(It.IsAny<GameTime>()), Times.Once(), 
            "Draw was not called on screen mock two");
    }

But the order in which I draw my objects in the production code does not matter. I could do one first, or two it doesn't matter. However it should matter as the draw order is important.

How do you (using Moq) ensure methods are called in a certain order?

Edit

I got rid of that test. The draw method has been removed from my unit tests. I'll just have to manually test it works. The reversing of the order though was taken into a seperate test class where it was tested so it's not all bad.

Thanks for the link about the feature they are looking into. I sure hope it gets added soon, very handy.

Solution 1:

I recently created Moq.Sequences which provides the ability to check ordering in Moq. You may want to read my post that describes the following:

• Supports method invocations, property setters and getters.
• Allows you to specify the number of times a specific call should be expected.
• Provides loops which allow you to group calls into a recurring group.
• Allows you to specify the the number of times a loop should be expected.
• Calls that are expected to be called in sequence can be inter-mixed with calls that are expected in any order.
• Multi-threaded support.

Typical usage looks like:

[Test]
public void Should_show_each_post_with_most_recent_first_using_sequences()
{
    var olderPost = new Post { DateTime = new DateTime(2010, 1, 1) };
    var newerPost = new Post { DateTime = new DateTime(2010, 1, 2) };
    var posts = new List<Post> { newerPost, olderPost };

    var mockView = new Mock<BlogView>();

    using (Sequence.Create())
    {
        mockView.Setup(v => v.ShowPost(newerPost)).InSequence();
        mockView.Setup(v => v.ShowPost(olderPost)).InSequence();

        new BlogPresenter(mockView.Object).Show(posts);
    }
}

Solution 2:

A simple solution using Moq CallBacks:

    [TestMethod]
    public void CallInOrder()
    {
        // Arrange
        string callOrder = "";

        var service = new Mock<MyService>();
        service.Setup(p=>p.FirstCall()).Returns(0).CallBack(()=>callOrder += "1");
        service.Setup(p=>p.SecondCall()).Returns(0).CallBack(()=>callOrder += "2");

        var sut = new Client(service);

        // Act
        sut.DoStuff();

        // Assert
        Assert.AreEqual("12", callOrder);
    }

Solution 3:

It appears that it's not currently implemented. See Issue 24: MockSequence. This thread discusses the issue.

You might consider revising your tests, though. I generally feel that testing order leads to fragile tests, as it's often testing implementation details.

EDIT: I'm not sure that this addresses the OP's question. Lucero's answer may be more helpful.

Solution 4:

Have a look at this blog post, it may solve your problem.