Improve action testing

[jamesrhester]

The current action uses a simple custom dictionary to check that the action works. It would be better to test functionality by checking out known-good dictionaries and running this check on them.

[vaitkus]

Sure, I mostly agree on this. Not sure if we need to check out the dictionaries each time, but having proper tests (some with passing dictionaries, some with failing ones) would be nice. Especially, if we could run the tests offline.

The current set up is a bit misleading, since the tests are marked as having the "failure" status while in fact the failure in this case is the expected behavior.

Not sure if I will get to update this anytime soon, but I will keep it in mind.