模拟抽象保护方法

Question

I have an abstract class:

public abstract class MyClass
{
    protected abstract bool IsSavable();

    protected bool IsExecutable()
    {
        //New mode or edit mode
        if (ViewMode == ViewMode.New || ViewMode == ViewMode.Edit)
        {
            return IsSavable();
        }

        //Search mode
        if (ViewMode == ViewMode.Search)
        {
            return true;
        }

        return false;
    }
}

I would like to unit test this class. Therefor I need to mock the "IsSavable" method. It should always return "true".

I know how to mock my abstract class with Moq. But how can I mock my abstract protected method so it returns true?

The function IsSavable is called in my abstract class by a concrete method (IsExecuteable). I would like to test this method. I know that most of you will recommend to test both in the class where "IsSavable" is implemented. Unfortunately this will be a lot of classes and I would like to test my method IsExecutable only once.

Answer 1

I would like to unit test this class. Therefor I need to mock the "IsSavable" method. It should always return "true".

No, that's a non-sequitur. You can just create a subclass which does what you want:

// Within your test code
class MyClassForTest : MyClass
{
    // TODO: Consider making this a property 
    protected override bool IsSavable()
    {
        return true;
    }
}

Then when you want to run a test, create an instance of MyClassForTest instead of just MyClass .

Personally I prefer to use mocking frameworks for dependencies rather than the classes I'm testing.

Answer 2

Just to corroborate what @Jon says - the fact that you are trying to Mock a protected method AND invoke another protected method on an abstract class is indicative of a smell.

But, by bringing out the heavy artillery - Moq's Protected() extensions, and again using direct reflection, to actually Invoke the SUT IsExecutable , it is actually possible to do what you want:

// Arrange
var mockMyClass = new Mock<MyClass>();
mockMyClass.Object.ViewMode = ViewMode.New; // I've made an assumption or two here ...
mockMyClass.Protected().Setup<bool>("IsSavable").Returns(true);

// Act!
var result = (bool)mockMyClass.Object.GetType().InvokeMember("IsExecutable",
    BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance,
    null,
    mockMyClass.Object,
    null);

// Assert
Assert.IsTrue(result);
mockMyClass.Protected().Verify<bool>("IsSavable", Times.Once());

But I personally would tend to rethink the design and method couplings at this point.

Answer 3

The quickest thing to do it to inherit from "MyClass" and override the IsSavable.

It might be bit harder in the test to differentiate what is being tested but it does the trick.

Furthermore you could think about the design - maybe there should be two classes -> one for Saveable behaviour and one for unSavable?