Question

Let’s say we are testing a class C which has 2 methods M1 and M2 where M1 calls M2 when executed.

Testing M2 is ok, but how can we test M1? The difficulty is that we need to mock M2 if I’m not misunderstanding things.

If so, how can we mock another method while testing a method defined in the same class?

[Edit]
Class C has no base classes.

Answer 1

You can do this by setting the CallBase property on the mock to true.

For example, if I have this class:

public class Foo
{
    public virtual string MethodA()
    {
        return "A";
    }
    public virtual string MethodB()
    {
        return MethodA() + "B";
    }
}

I can setup MethodA and call MethodB:

[Fact]
public void RunTest()
{
    Mock<Foo> mockFoo = new Mock<Foo>();
    mockFoo.Setup(x => x.MethodA()).Returns("Mock");
    mockFoo.CallBase = true;

    string result = mockFoo.Object.MethodB();

    Assert.Equal("MockB", result);
}