Not sure the fix is right. Here is what I found: issue is connected
with line
first.prefix = prefix[comment.consumed :]
in `comments.py`. `first.prefix` is a prefix of the line, that ends
with `# fmt: skip`, but `comment.consumed` is the length of the
`" # fmt: skip"` string. If prefix length is greater than 14,
`first.prefix` will grow every time we apply formatting.
Fixes#2254
There's three optimizations in this commit:
1. Don't check if Black's output is stable or equivalant if no changes
were made in the first place. It's not like passing the same code
(for both source and actual) through black.assert_equivalent or
black.assert_stable is useful. It's not a big deal for the smaller
tests, but it eats a lot of time in tests/test_format.py since
its test cases are big. This is also closer to how Black works IRL.
2. Use a smaller file for `test_root_logger_not_used_directly` since
the logging it's checking happens during blib2to3's startup so the
file doesn't really matter.
3. If we're checking a file is formatting (i.e. test_source_is_formatted)
don't run Black over it again with `black.format_file_in_place`.
`tests/test_format.py::TestSimpleFormat.check_file` is good enough.
* 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>