Stubtest cannot find module with stubs in separate directory

[rayzchen]

Bug Report

Running stubtest --mypy-config-file pyproject.toml foo yields foo failed to import, ModuleNotFoundError: No module named 'foo'

To Reproduce

1. Clone https://github.com/rayzchen/stubtest-bug
2. Run stubtest --mypy-config-file pyproject.toml foo

Expected Behavior

Stubtest finds the foo module

Actual Behavior

error: foo failed to import, ModuleNotFoundError: No module named 'foo'
Stub: in file stubs\foo\__init__.pyi:1
MypyFile:1(
  stubs/foo/__init__.pyi)
Runtime:
MISSING

error: foo.bar failed to import, ModuleNotFoundError: No module named 'foo'
Stub: in file stubs\foo\bar\__init__.pyi:1
MypyFile:1(
  stubs/foo/bar/__init__.pyi)
Runtime:
MISSING

error: foo.bar.baz failed to import, ModuleNotFoundError: No module named 'foo'
Stub: in file stubs\foo\bar\baz.pyi:1
MypyFile:1(
  stubs/foo/bar/baz.pyi)
Runtime:
MISSING

Found 3 errors (checked 3 modules)

Your Environment

• Mypy version used: 1.3.0
• Mypy command-line flags: N/A (used stubtest)
• Mypy configuration options from mypy.ini (and other config files): mypy_path = "stubs/"
• Python version used: 3.10.6

[hauntsaninja]

This is just Python's normal import finding logic. You need to either a) install your project, b) set the PYTHONPATH environment variable or something, c) use python -m mypy.stubtest instead of stubtest and rely on Python's implicit addition of cwd to the python path

[rayzchen]

Does running stubtest as a python entrypoint not add . to the pythonpath? Shouldn't running stubtest foo try to import foo since the argument to stubtest is called modules?

[hauntsaninja]

From https://docs.python.org/3/library/sys_path_init.html

The first entry in the module search path is the directory that contains the input script, if there is one. Otherwise, the first entry is the current directory, which is the case when executing the interactive shell, a -c command, or -m module.

This means you e.g. get bin/ in your virtual environment added to sys.path. Running stubtest does try to import foo, but you need to tell Python where to find foo using one of the three options I mention above.

[rayzchen]

Alright, thank you for the info.

[hauntsaninja]

#15398 will improve the error message here