Every assertion should be thought from the standpoint of
- What was expected
- What actually happened
Translation: assertTrue should always, always have a message.
Consider the following:
This will only return “assertion failed”. Which is great, but how do we know what happened? If this is buried on one of the lunt automated remote builds, how am I supposed to know what is going wrong? Which is the expected? What actually happened?
A much better version of the same looks like this:
assertTrue( "Was expecting something like " + myController.getSuccessView() + " but was " + mv.getViewName(), mv.getViewName() .startsWith(myController.getSuccessView()));
Same assertion, but now it tells me more specifically what’s going on and I can fix bugs with it. Once I set this on the test, it becomes easy to see what was going on.
I recently had a Saturday with some other Bay Area developers where we did a lot of thinking about testing, so expect some more advice in the future as I collect my notes.
Remember the goal of unit tests is to “find bugs” (thanks Harry!). An assertion without an associated message merely notifies you that a bug occurred but doesn’t actually “find it”. As you are writing your unit tests, make sure you find it as well.