Today I found myself at a crossroads regarding testing. In my efforts to have pure unit tests, I had created tests with no assertions. Each test contained a mock object that verified multiple expectations, but no assertions. While each mock expectation could be thought of as an assertion, is it really a good idea to test the algorithm?

I say no.

The algorithm shouldn’t matter. The only thing that should matter is the input and output of each function.

Now I found my tests are much more stable and not nearly as much of a pain to write. I am setting up my expectations for input and output, but not regarding how to get there.

As you might expect though, the tests aren’t isolated to one class. They cross a few class boundaries, but not layer boundaries.

Have I traded one evil for another? I honestly don’t know, but I am going with my gut, and what makes sense. Having no assertions isn’t right in my opinion. What do you think?