When using pytest's test collector, any class with a name starting with
Test is collected. If it notices that the class has an `__init__` member
then it skips it with a warning since it's probably a false positive.
This isn't a big deal, but we can avoid warnings like this:
test/test_ui_importer.py:33
beets/test/test_ui_importer.py:33: PytestCollectionWarning: cannot collect test class 'TestTerminalImportSession' because it has a __init__ constructor
class TestTerminalImportSession(TerminalImportSession):
simply by renaming TestX to XFixture.
This was a vestige from when we used to need the unittest2 library for pre-2.7
compatibility. Now that we require Python 2.7, we aren't using that library
and this indirection wasn't doing any good.
This reverts commit 9c41c39913.
That commit used byte strings for the `if __name__ == '__main__'` pattern,
which was necessary when we were doing unicode_literals. But it is wrong on
Python 3, and now that we're liberated from unicode_literals, we need to go
back to native strings for this comparison.
Include import of __future__ features division, absolute_imports and
print_function everywhere. Don't add unicode_literals yet for it is
harder to convert.
Goal is smoothing the transition to python 3.
