Test coverage for GitTempDir

[smashwilson]

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Description of the Change

Adds test coverage for GitTempDir to prevent coverage flapping in unrelated pull requests.

Alternate Designs

I could have only covered the lines that weren't hit by other codepaths, but it's a small class so I just covered the whole thing.

Benefits

GitTempDir is one of the culprits in test coverage flapping that we see on unrelated PRs. This is one step toward minimizing those changes and keeping CodeCov output relevent.

Possible Drawbacks

N/A

Applicable Issues

N/A

Metrics

N/A

Tests

This should raise GitTempDir's coverage to 100%.

Documentation

N/A

Release Notes

N/A

User Experience Research (Optional)

N/A

[codecov]

Codecov Report

Merging #1901 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1901      +/-   ##
==========================================
- Coverage   91.09%   91.05%   -0.05%     
==========================================
  Files         185      185              
  Lines       10719    10719              
  Branches     1575     1575              
==========================================
- Hits         9765     9760       -5     
- Misses        954      959       +5

Impacted Files	Coverage Δ
lib/models/conflicts/side.js	92.18% <0%> (-4.69%)	⬇️
lib/atom/decoration.js	84.33% <0%> (-2.41%)	⬇️
lib/controllers/editor-conflict-controller.js	94.94% <0%> (-1.02%)	⬇️
lib/git-temp-dir.js	100% <0%> (+3.03%)	⬆️

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[smashwilson]

Looks like we're good 👌

[annthurium]

thanks for making our test coverage more stable! I have a question or two for my own education but nothing blocking.

Why were these files causing flapping in the first place? Were there timing issues or something, where sometimes we met certain conditions and sometimes not?

[annthurium]

just for my own education...

you assign root = tempDir.getRootPath on line 11, and then assert that that these are still equal. With this assertion, are you testing that ensure() does not change the root path?

[smashwilson]

With this assertion, are you testing that ensure() does not change the root path?

Yup, exactly. I wanted to assert that multiple calls to ensure() wouldn't create new temp directories, basically.

[annthurium]

fun regex. oh, windows.

[smashwilson]

Named pipes are fun 🙃

[smashwilson]

Why were these files causing flapping in the first place? Were there timing issues or something, where sometimes we met certain conditions and sometimes not?

GitTempDir was only tested incidentally through GitShellOutStrategy and Repository tests, so we had a few lines that weren't being explicitly exercised. Getting us to full coverage with an explicit test is the best way to make sure these don't fall through the cracks.