External Python packages interfacing beets may want to use an in-memory
beets library instance for testing beets-related code.
The `TestHelper` class is very helpful for this purpose.
Previously `TestHelper` was located in the `test/` directory.
Now it is part of `beets` itself (`beets.test.helper.TestHelper`) and
can be easily imported.
this replaces assertions of the form
self.assertTrue(os.path.exists(syspath(path)))
by
self.assertExists(path)
which includes the syspath conversion and is much easier to read.
Occurences where located using
git grep -E 'assert(True|False).*(isdir|isfile|exist)'
these are mostly in the tests, which didn't cause issues since the
affected directories usually have nice ASCII paths. For consistency, it
is nicer to always invoke syspath. That also avoids deprecation warnings
for the bytestring interfaces on Python <= 3.5. The bytestring
interfaces were undeprecated with PEP 529 in Python 3.6, such that we
didn't observe any actual failures.
The move functions in library.py and manipule_files in importer.py where
changed to use a single parameter for the file operation instead of
multiple boolean flags.
A typo in the documentation of the Album.move and Item.move functions
confusing True and False when describing the store parameter was fixed
as well.
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.
