It baffles me that the original comments for the article express so much agreement. "Exhibit A" doesn't have anything to do with mocking. In "Exhibit B" he tries to test operations on values with mocks, which is never a good idea. Ironically, the multiplication example at the bottom shows how constructed his example is. Of course I've seen people in the "mocking world" who write code like this, but that's not an argument against mocking. I think "Exhibit C" is actually valid, but his solution requires a self written AOP framework and the test still relies on implementation details.