mypy warning: tests/__init__.py:34: error: Cannot assign to a method

[hjmjohnson]

Describe the bug
mypy static checker provides warning:

tests/__init__.py:34: error: Cannot assign to a method

To Reproduce
Steps to reproduce the behavior:

1. Modify setup.cfg and enable error checking for tests/__init__.py
2. MYPYPATH=$(pwd)/monai mypy $(pwd)

Expected behavior
No warnings produced.

[hjmjohnson]

@benjamin-gorman Could you try to address this warning?

[ghost]

Work arounds

# preferable (see context)

setattr(unittest.case._AssertWarnsContext, "__enter__", _enter_pr_4800)

# but has flake8-bugbear error
# B010 Do not call setattr with a constant attribute value, it is not any safer than normal property access.

# ignore the specific error

unittest.case._AssertWarnsContext.__enter__ = _enter_pr_4800  # type: ignore[assignment]

Context

I prefer setattr over using # type: ignore. Mypy won't complain about it. This is something we could discuss in the common issues section in the docs.

python/mypy#2427 (comment)

The has been no progress recently. The workarounds discussed above (setattr or # type: ignore) are still the recommended ways to deal with this.

python/mypy#2427 (comment)

Progression of _enter_pr_4800

• Present in master, 3.7, 3.8
• Missing from 3.5, 3.6, 3.9

Alternatively

There is the typing.Protocol fix but that would require a .pyi file and seems like overkill.

[wyli]

the workaround is well documented

MONAI/tests/__init__.py

Lines 32 to 36 in bbc2da5

	# workaround for https://bugs.python.org/issue29620
	try:
	# Suppression for issue #494: tests/__init__.py:34: error: Cannot assign to a method
	unittest.case._AssertWarnsContext.__enter__ = _enter_pr_4800 # type: ignore
	except AttributeError:

closing this issue