Some quick questions, coming back to this with fresh eyes.
Can't spend time on this now as I'm not in the current sprint.
 - Aren't these test just testing ```_CubeSignature.match```?
 - Why the addition of ```test_CoordSignature.py``` but no ```test_CubeSignature.py```?
 - Should all, or most of, the tests in this new file belong in the two files mentioned above?