isort: bug in sorting sub-package modules

[spaceone]

.isort.cfg

[settings]
known_first_party=foo.bar,baz
known_third_party=foo,blub,blah

valid isort-compatible code:

import sys

import blah
import blub
import foo
from foo import bar, baz

import baz
import foo.bar
from foo.bar import blah, blub

pyproject.toml:

[tool.ruff]
select = ["I"]
[tool.ruff.isort]
known-first-party = ["foo.bar", "baz"]
known-third-party = ["foo", "blub", "blah"]

$ ruff --fix --diff foo.py
--- foo.py
+++ foo.py
@@ -3,8 +3,8 @@
 import blah
 import blub
 import foo
+import foo.bar
 from foo import bar, baz
+from foo.bar import blah, blub
 
 import baz
-import foo.bar
-from foo.bar import blah, blub

Would fix 1 error.

[charliermarsh]

I'm tempted to call this unsupported. Isn't the issue here that you're marking a module and one of its submodules as third- and first-party respectively?

[spaceone]

ruff should be isort compatible, right?

we have a main package foo with many different sub-packages as foo.bar or foo.blub.
In the code of foo.bar we want that foo.bar is a first-party module and everything else (foo and foo.blub) is just a third-party module.

[charliermarsh]

The intent is to be isort-compatible, but we do deviate in a small number of cases, and this to me seems like a situation where there isn't a clear definition of correct behavior. I'd be open to doing what isort does rather than our current behavior, but I won't personally prioritize it.

[spaceone]

I provided a fix in #3064. Isort has a test case for it: https://github.com/PyCQA/isort/blob/main/tests/unit/test_isort.py#L2213-L2304 → test_placement_control() and test_custom_sections()

[astaric]

One usecase where we encounter the same issue are namespace packages. We have different packages (in different repositories) share the same namespace package.

With the following config, isort lists namespace.packageA imports in the last section while all other namespace imports are listed in the third party section above.

known_first_party = namespace.packageA
default_section = THIRDPARTY

I played around with known_first_party and known_third_party options but I cannot get packages with the same namespace prefix to end up in different sections.