Use pre-commit

[kurtmckee]

git pre-commit hooks can catch linting issues on developer PCs before they're ever committed to the repo. pre-commit is a widely-used tool that allows projects to specify all of the linters they want to run before each commit.

This PR introduces a pre-commit config that will enforce standard text linting; black, isort, and editorconfig linting; and idiomatic Python 3.6+ syntax.

• Developers with the pre-commit tool installed can simply run pre-commit install in the dotbot repo, and from that point forward git will run the tool prior to each commit so the files are linted and auto-fixed.
• The dotbot repo can be registered with the pre-commit.ci service so that it auto-checks -- and, by default, autofixes! -- incoming PRs. It will also open PRs to keep the pre-commit hook versions updated on a regular basis. I STRONGLY recommend doing this!

[codecov-commenter]

Codecov Report

Patch coverage: 80.55% and project coverage change: +0.01% 🎉

Comparison is base (840cd16) 89.13% compared to head (5246ca2) 89.14%.
Report is 4 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #347      +/-   ##
==========================================
+ Coverage   89.13%   89.14%   +0.01%     
==========================================
  Files          33       33              
  Lines        1620     1622       +2     
  Branches      306      307       +1     
==========================================
+ Hits         1444     1446       +2     
  Misses        124      124              
  Partials       52       52              

Files Changed	Coverage Δ
dotbot/cli.py	67.36% <0.00%> (ø)
dotbot/util/string.py	25.00% <0.00%> (ø)
dotbot/plugins/link.py	86.95% <50.00%> (ø)
dotbot/messenger/messenger.py	65.11% <100.00%> (ø)
dotbot/plugins/clean.py	91.30% <100.00%> (ø)
dotbot/plugins/create.py	75.60% <100.00%> (ø)
dotbot/plugins/shell.py	94.82% <100.00%> (ø)
dotbot/util/common.py	100.00% <100.00%> (ø)
dotbot/util/singleton.py	100.00% <100.00%> (ø)
tests/conftest.py	92.35% <100.00%> (+0.09%)	⬆️
... and 4 more

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[kurtmckee]

If unfamiliar with pre-commit, you can do the following to test it out:

• Checkout this branch
• Install pre-commit (for example, in an activated virtual environment using pip install pre-commit or using pipx -- which I strongly recommend -- using pipx install pre-commit)
• Enable pre-commit in the dotbot repo (run pre-commit install)
• Modify two files by rearranging their imports.
• Stage one of the two files (but not both) for a commit.
• Try to commit the file.

What you'll see is that pre-commit runs isort against the one staged file (but not both!), isort lints and fixes the file's imports, and the commit fails. Notably, pre-commit stashes changes temporarily so only what you've staged gets checked.

For example, this is the output I see locally when I rearrange the imports in cli.py and another file, but only stage cli.py in a commit:

[WARNING] Unstaged files detected.
[INFO] Stashing unstaged files to C:\Users\Kurt\.cache\pre-commit\patch1694373671-15164.
check yaml...........................................(no files to check)Skipped
fix end of files.........................................................Passed
mixed line ending........................................................Passed
trim trailing whitespace.................................................Passed
Enforce Python 3.6 idioms................................................Passed
black....................................................................Passed
isort....................................................................Failed
- hook id: isort
- files were modified by this hook

Fixing C:\Users\Kurt\Documents\dev\dotbot\dotbot\cli.py

Check .editorconfig rules................................................Passed
[INFO] Restored changes from C:\Users\Kurt\.cache\pre-commit\patch1694373671-15164.

I have to stage isort's fixes to my commit before I can successfully commit.

[kurtmckee]

Hi Anish! I hope your year is off to a good start!

I'm going to close this PR to reduce cognitive load.

Thanks for your work on dotbot!