Type checking with mypy

[dougiesquire]

I've set up type checking with mypy, and I have it running successfully locally with a few minor changes (that is, mypy xhistogram passes succesfully).

I've added mypy into pre-commit, but we're failing here. The issue is that when run with pre-commit, mypy seems to want to check versioneer.py, which sits in the base directory. I'm not sure why and I can't work out how to exclude it. What I've tried:

• Adding an exclude hook to .pre-commit-config.yaml. This seems to have no impact, maybe because of https://github.com/pre-commit/mirrors-mypy/issues/1.
• Various attempts at syntax to exclude it in our setup.cfg. mypy allows exclusion via the configuration file, but it expects users to specify exclusion of modules (https://mypy.readthedocs.io/en/stable/config_file.html). The versioneer.py file is not part of the xhistogram module so I can't work out any syntax to exclude it.

I'm sure I'm doing something daft, but I'd appreciate some help. Once I can get mypy into our CI, then I can dive in and try and add static typing to xhistogram methods.

[codecov[bot]]

Codecov Report

Merging #38 (5351223) into master (40b6f3a) will not change coverage. The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master      #38   +/-   ##
=======================================
  Coverage   94.41%   94.41%           
=======================================
  Files           3        3           
  Lines         215      215           
  Branches       58       58           
=======================================
  Hits          203      203           
  Misses          8        8           
  Partials        4        4           

Impacted Files	Coverage Δ
xhistogram/duck_array_ops.py	78.26% <0.00%> (ø)

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[dougiesquire]

@jrbourbeau, @rabernat perhaps you have some insight here?

[dougiesquire]

Following these recommendations, I've also just tried setting

[mypy]
exclude = '/versioneer\.py$'

within setup.cfg without success.

[dougiesquire]

For the pre-commit hook, you might try specifying explicitly specifying the files to check instead of which ones to exclude

Thanks @jrbourbeau, works great! Though we're now failing some of our tests and I'm not yet sure why. The tests are passing locally...