FakeItEasy - I cannot see if a protected method was called when the caller method is protected overriden

Question

I'm new to FakeItEasy, sorry if the solution is obvious.

This is the simplified code which reproduces the problem:

I have a base class:

public abstract class BaseClass
    {
        public void Do()
        {
            Do_Override();
        }

        protected abstract void Do_Override();
    }

and a derived one:

  public class ImplementingClass: BaseClass
    {
        protected override void Do_Override()
        {
            ProtectedDo();
        }

        protected virtual void ProtectedDo()
        {

        }        
    }

In my test I want to see if ProtectedDo() was called. I've tried to test in two ways, but tests are failing with the same message:

1st. In debug mode it is not entering in Do_Override()

 public class ImplementingClassShould
    {
        [Fact]
        public void Run_ProtectedDo()
        {
            var fake = A.Fake<ImplementingClass>();
            fake.Do();
            A.CallTo(fake).Where(_ => _.Method.Name == "ProtectedDo").MustHaveHappened();

        }
     }

2nd. In debug mode it is entering in Do_Override()

 public class ImplementingClassShould
    {    
        [Fact]
        public void Run_ProtectedDo_V2()
        {
            var sut = new ImplementingClass();
            var sutFakeWrapper = A.Fake<ImplementingClass>(_ => _.Wrapping(sut));
            sutFakeWrapper.Do();
            A.CallTo(sutFakeWrapper).Where(_ => _.Method.Name == "ProtectedDo").MustHaveHappened();

        }        
    }

Fail message:

Hi, @fmm. I like the simplified repro, but it's generally a good idea to indicate what went wrong in your experience. For example, why don't you think your code is working? — Blair Conrad, Jun 30 '21 at 10:37
Hi, @BlairConrad. I've update my question with the message of test failing. Also my 2nd try to test. Thanks. — cdi, Jun 30 '21 at 10:50

Blair Conrad · Accepted Answer · 2022-02-10T16:01:04.577

Your test is perfectly good, as far as it goes. If you run it, it'll tell you that ProtectedDo was not called, which is accurate. Because Do_Override is virtual, FakeItEasy intercepts the call. (The protectedness doesn't affect things in this case.)

If you don't want Do_Override to be intercepted by FakeItEasy, you should configure the Fake to call the base method instead of handling the call itself:

[Fact]
public void Run_ProtectedDo()
{
    var fake = A.Fake<ImplementingClass>();

    A.CallTo(fake).Where(_ => _.Method.Name == "Do_Override").CallsBaseMethod();

    fake.Do();
    A.CallTo(fake).Where(_ => _.Method.Name == "ProtectedDo").MustHaveHappened();

}

Update in light of the newly added Run_ProtectedDo_V2 test:

I expect you know this already, @fmm, but the test still fails. This is because when sutFakeWrapper.Do is called, it forwards to the wrapped sut.Do. Since sut is a concrete ImplementingClass, it calls its Do_Override, which calls its ProtectedDo, so it's possible to debug into a ProtectedDo method call. Only it's sut.ProtectedDo, not sutFakeWrapper.ProtectedDo. Hence the test failure.

FakeItEasy - I cannot see if a protected method was called when the caller method is protected overriden

1 Answers1