test: add docstrings mypy check

[LiamConnors]

What type of PR is this? (check all applicable)

• 💾 Refactor
• ✨ Feature
• 🐛 Bug Fix
• 🔧 Optimization
• 📝 Documentation
• ✅ Test
• 🐳 Other

Related issues

• Related issue chore: find a way to type-check and lint docstrings #1410
• Closes #<issue number>

Checklist

• Code follows style guide (ruff)
• Tests added
• Documented the changes

If you have comments or can explain your changes, please do so below

[LiamConnors]

The test takes a bit too long to run (15-20minutes). Will see if there's another way to go about it.

It did find issues though

Checking narwhals/stable/v1/__init__.py all
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py col
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py nth
<string>:17: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py len
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py lit
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py min
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py max
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py mean
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py median
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py sum
<string>:15: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py sum_horizontal
<string>:17: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py all_horizontal
<string>:20: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

Checking narwhals/stable/v1/__init__.py any_horizontal
<string>:20: error: Name "IntoFrameT" is not defined  [name-defined]
Found 1 error in 1 file (checked 1 source file)

[EdAbati]

Thank @LiamConnors for looking into this! 👏

I think the slowness comes from running mypy sequentially for each docstring.

For each module we could try to add all its docstrings into a separate temp file, and pass all these files at once to mypy. But we would need to show which files and docstring generates an error somehow. It'd be nice to have something like:

narwhals/stable/v1/__init__.py:any_horizontal:<line_no> error: Name "IntoFrameT" is not defined  [name-defined]

Is there something we can learn from nbqa @MarcoGorelli? If I am not mistaken, it's kind of similar, instead of multiple cells here we have multiple docstrings

[MarcoGorelli]

thanks a tonne for doing this!

It did find issues though

nice, I did suspect we'd find something which --doctest-modules wasn't picking up

Maybe even just running python on each example would be a good start, and be fast enough?

[LiamConnors]

Thanks @EdAbati and @MarcoGorelli for the feedback! Will take another look