* Move string-related utility to functions to strings.py, const.py
* Move Leaf/Node-related functionality to nodes.py
* Move comment-related functions to comments.py
* Move caching to cache.py and Mode/TargetVersion/Feature to mode.py
* Move some leftover functions to nodes.py, comments.py, strings.py
* Add missing files to source list for test runs
* Move line-related functionality into lines.py, brackets into brackets.py
* Move transformers to trans.py
* Move file handling, output, parsing, concurrency, debug, and report
* Move two more functions to nodes.py
* Add CHANGES
* Add numeric.py
* Add linegen.py
* More docstrings
* Include new files in tests
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
This is a follow-up of #2203 that uses a pytest marker instead of a bunch of
`skipUnless`. Similarly to the Python 2 tests, they are running by default and
will crash on an unsuspecting contributor with missing dependencies. This is
by design, we WANT contributors to test everything. Unless we actually don't
and then we can run:
pytest --run-optional=no_blackd
Relatedly, bump required aiohttp to 3.6.0 at least to get rid of expected
failures on Python 3.8 (see 6b5eb7d465).
