[jkubicek]

I see two advantages in creating tests to check output

    1. You did the work to generate consistent output from the code as a whole, plus output intermediate steps. Writing those into a test lets future folks make use of the same tests.
    2. Having the tests in place prevents people from making changes that accidentally change the output

Don't get me wrong, tests that just compare two large blobs of output aren't fun to work with, but they _can_ be useful, and are an OK intermediate stage while you get proper unit tests written.