Tests: fix database test to actually pass mode through

[akx]

It looks like ever since the mode argument was surfaced in 06b1b62 a decade ago, it was actually never tested; self.mode was not used in BaseTestReader.

In addition, 3f8c7ca adds support for MODE_FD, but the test suite it added is empty, so it's simply removed here.

This also switches from unittest self.assert*s to plain pytest asserts and pytest.raises()es.

[oschwald]

Good catch on the mode test! It looks like the original change was not completely implemented. That said, doing all the different tests with the different modes seems unnecessary. In the maxminddb library, the modes significantly change the behavior, but in this library there is no behavior change besides passing the modes through to maxminddb, which this doesn't even end up confirming. It would be better to have a single test for that. I added this in #179.

In general, I would encourage you to submit a single PR for each change you are proposing. This PR contains several unrelated changes, e.g., moving to pytest asserts, making it hard to review each change individually. Also, for larger changes, it usually makes more sense to discuss them first before making a PR.

[akx]

e.g., moving to pytest asserts, making it hard to review each change individually.

Had to be done (and in fact it had been done as part of #180, but I wanted to separate this from that refactoring). parametrize doesn't work with unittest based tests, and self.assert* do not exist on non-unittest suites.