Well, there are places in ExUnit where we expect the format of suite_finished to be an integer, it just happens those particular tests are not going through it, but it may break in the future. Basically, if we had a type system, the code wouldn't compile. :P

The only way I can see to solve this, by not exposing the gen server, is by storing the return result in the process dictionary. However, if we have to expose the gen server, I don't see an issue with it either, because that's exactly what we need to write the test (and exactly why we have a formatter specific for tests).