Black does not fix missing newline (flake8 E302) before comment + class definition

[kerrickstaley]

Describe the bug

In the following code:

import math

# a most excellent class
class MyClass:
    PI = math.pi

Black fails to add an extra newline before the comment. This causes flake8 to give an E302 error.

Black does add a newline if you delete the comment, so I think this is an issue with Black.

To Reproduce
Run this in Bash on a Linux/Unix system:

cat > foo.py <<EOF
import math

# a most excellent class
class MyClass:
    PI = math.pi
EOF

python3 -m black foo.py
python3 -m flake8 foo.py

black will output

All done! ✨ 🍰 ✨
1 file left unchanged.

and flake8 will output

foo.py:4:1: E302 expected 2 blank lines, found 1

Expected behavior

Black adds a newline, and flake8 does not produce an error.

Environment

$ python3 -m black --version
python -m black, 22.10.0 (compiled: yes)
Python (CPython) 3.10.8
$ python3 -m flake8 --version                  
5.0.4 (mccabe: 0.7.0, pycodestyle: 2.9.1, pyflakes: 2.5.0) CPython 3.10.8 on Darwin
$ python3 --version
Python 3.10.8
$ sw_vers
ProductName:	macOS
ProductVersion:	12.5
BuildVersion:	21G72

[felix-hilden]

Hi, this has been just fixed in --preview (playground example, #3302) coming your way in the next release. I'll close this issue as a duplicate!