Fix /discovery-methods endpoint

[ikalnytskyi]

Currently there're two issues with that endpoint:

• It uses DBAPI.get_discovery_methods() without arguments but it
  does receive one.
• It expects DBAPI.get_discovery_methods() to return a list of
  supported discovery methods, but it returns a dictionary instead.

The fix for the first one is to get rid of unused argument, and for the
second one - return a list instead of dictionary. The funny thing is, we
have a correct mock in tests.. it's a production code that's broken.

[sc68cal]

OK - can you add a unit test to https://github.com/sc68cal/Kostyor/blob/master/kostyor/tests/unit/test_db_api.py to catch this?

[ikalnytskyi]

Sure.

[ikalnytskyi]

@sc68cal Well, I can add test like this:

    def test_discovery_methods(self):
        methods = db_api.get_discovery_methods()
        self.assertItemEquals(methods, [constants.OPENSTACK])

but it won't catch anything. I think we should start testing API without mocking database. It's cheap and will prevent us from possible errors. What do you think?

[sc68cal]

We already mock the database in the unit tests for the REST API. Please create a test that checks the return value of db_api.get_discovery_methods()

[ikalnytskyi]

@sc68cal i'm proposing the vice versa: do not mock it. Otherwise, it won't cover the issue because we simply won't check integration between db_api and rest_api.

Example:

• rest_api test mocks db_api to return correct data. test is passed.
• db_api test checks returned data. test is passed.
• however, db_api may return data not in format that's expected by rest_api module. this is exactly the case of this bug.