AssertWasCalled on dynamic in Rhino Mocks

Question

Is there any way to do an AssertWasCalled on a dynamic in RhinoMocks, like this:

    var testObject = MockRepository.GenerateStub<dynamic>();
    testObject.AssertWasCalled(x=>x.MyMethod(Arg<string>.Matches(y=>y == "TestString"));

Answer 1

As I mentioned in my comments, I don't think most proxy based Mock object frameworks (RhinoMock/Moq) support dynamic verification. You may try a profiler based framework such as TypeMock etc, but they are not free.

So the only option I think is to go back to old school where we wrote hand written stubs/mocks.

Create another layer of indirection. A technique in many places describe as extract and override. So you simply create a hand written mock to verify this behaviour.

a. Create a simple/silly protected virtual member which wraps your dynamic call

System Under Test (SUT) :

  public class Sut {
    private dynamic _d;

    public Sut(dynamic d) {
        _d = d;
    }

    public void M() {
        MyMethod();
    }

    protected virtual void MyMethod() {
        _d.MyMethod();
    }
 }

b. In your Unit Test, create a testable version of Sut by inheriting from Sut. Important : It should only contain the overridden method, but nothing else (except the bool to ensure the overridden method was called)

public class TestableSutWithDynamic : Sut {
    public bool WasCalled = false;

    protected override void MyMethod() {
        WasCalled = true;
    }
}

c. Then simply assert against the testable Sut

    [Test]
    public void VerifyMyMethodIsCalled() {
        var sut = new TestableSutWithDynamic();

        sut.M();

        Assert.True(sut.WasCalled);
    }