Change default --app-dir from from "." (dot) to "" (empty string).

[mila]

Both the dot and empty string are interpreted as the current working directory but Python, but the dot causes ugly __file__ of imported modules. The empty string is consistent with Python behavior, inserting an empy string to sys.path when running interactively.

Discussion: #1814

[Kludex]

Does os.getcwd() instead empty string has the same behavior here?

Also, can we add a test for it? Just to validate exactly what you said in the discussion. Ideally, the test would fail on master right now, and pass here.

[mila]

Does os.getcwd() instead empty string has the same behavior here?

The behavior would be different if the application changed cwd at runtime. Both "." and "" mean the cwd at the time of import, os.getcwd() would freeze the value.

Also, can we add a test for it? Just to validate exactly what you said in the discussion. Ideally, the test would fail on master right now, and pass here.

I was considering that and but I am not sure what I should test and whether it is worth it.

Today, a test for --app-dir asserts that sys.path is modified. I can copy this test and assert that the empty string is inserted there. But that would just ensure that default value is honored by Click.

It would be safer to test that it is possible to import an app from --app-dir (empty or custom). But all CLI tests now use mocks, so I did not want to introduce a test that would run a real server.

[Kludex]

It's fine. 👍

Thanks! 🙏

Ref.: https://docs.python.org/3/library/sys.html#sys.path