Does ruff ignore private modules?

[tazr]

I have a library with a private module like so:

# _foo.py
def foo(x:int) -> None:
  pass

When running ruff on my project,

# at my project root
uvx ruff check --isolated --select D .

I get no error. However renaming _foo.py -> foo.py returns errors D100 and D103. Is this the expected? How can I run ruff on private modules as well as public ones?

[amyreese]

I suspect this is a behavior of the D1xx rules, not Ruff.

If I have both foo.py and _foo.py that trigger an F401 error, then Ruff reports that in both files:

$ uvx ruff check --isolated --select F .
F401 [*] `os` imported but unused
 --> _foo.py:1:8
  |
1 | import os
  |        ^^
  |
help: Remove unused import: `os`

F401 [*] `os` imported but unused
 --> foo.py:1:8
  |
1 | import os
  |        ^^
  |
help: Remove unused import: `os`

Found 2 errors.
[*] 2 fixable with the `--fix` option.
> [1]

You can confirm what files Ruff is inspecting with the --show-files flag:

$ uvx ruff check --isolated --select F . --show-files
/Users/amethyst/scratch/ruff/_foo.py
/Users/amethyst/scratch/ruff/foo.py