public CallbackOnly()
{
stub = new ThingStub();
fake = A.Fake <IThingy>();
A.CallTo(() => fake.DoSomething()).Invokes(f => fakeCalled = true);
var mockSetup = new Mock <IThingy>();
mockSetup.Setup(m => m.DoSomething()).Callback(() => mockCalled = true);
mock = mockSetup.Object;
sub = Substitute.For <IThingy>();
sub.When(s => s.DoSomething()).Do(c => subCalled = true);
var rock = Rock.Create <IThingy>();
rock.Handle(r => r.DoSomething(), () => rockCalled = true);
chunk = rock.Make();
}