You are missing Tom’s point. The “All Tests Passed” messages means that the unit tests in the notebook all passed. But Tom’s point is that those tests don’t catch all possible errors. Yes, they could do better, but we have to deal with them as they are. We have reported this as a bug, but writing good test cases is not as easy as you might think.
One error I know of that is not caught by the tests in the notebook is forgetting to use the stride on the pool forward function.