Develop phpunit tests for BuildData

I suggest you might as well commit this immediately. Then you can enable automated testing on d.o. and we can all see how the first test performs! Having a failing test but with automated testing running is better than no tests, and things can only get better from that point.

In testSetModuleType($actual, $expected)

   if ($expected !== FALSE) {
     $this->buildData->setModuleType($actual);
     $this->assertEquals($expected, $actual);
   }

The assertEquals will always pass, as you are sending the same values in to the function. I think you probably meant

     $this->assertEquals($expected, $this->buildData->getModuleType();

That's a great start. Well done!

I notice that the default core version for testing is 8.3. It might be useful to run a one-off custom test on D8.1 and D8.2 as I have found there to be differing results sometimes. It would be useful to have this information.

That's useful to see those extra test configurations passing. I have commented on #2813495: Test fail because supervisorctl: command not found as I've seen exactly that problem with Scheduler.

RTBC for sure, but you have already committed the code, so I will let you have the pleasure of setting it to 'fixed' ;-)

That's interesting. It must be due to continual assessment testing - I set the status to RTBC but I did not manually ask for re-testing of the patches, that must have been automatic. Now the status has been reverted to 'needs work' because the patches no longer apply, as the work has already been committed. I won't set it to RTBC again, as I expect that may trigger another set of tests.