Add a test for uncovered branch in the writer module

[atugushev]

There was uncovered unnecessary branch. Now it's 100% coverage in the writer module.

[codecov]

Codecov Report

Merging #1101 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1101   +/-   ##
=======================================
  Coverage   99.42%   99.43%           
=======================================
  Files          34       34           
  Lines        2441     2458   +17     
  Branches      302      302           
=======================================
+ Hits         2427     2444   +17     
  Misses          8        8           
  Partials        6        6           

Impacted Files	Coverage Δ
tests/test_writer.py	100.00% <100.00%> (ø)
piptools/repositories/pypi.py	93.14% <0.00%> (-0.58%)	⬇️
piptools/resolver.py	100.00% <0.00%> (ø)
tests/test_cli_compile.py	100.00% <0.00%> (ø)
piptools/writer.py	100.00% <0.00%> (+0.74%)	⬆️

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[AndydeCleyre]

I had a look to understand the cases covered or not, and figured out that this change would result in a false-positive warning in the case that:

• --generate-hashes is passed, and
• only editable requirements are present

The editable requirements don't (can't) get hashed, and if there were also hashed reqs then pip would refuse to cooperate, but since none of them are, the results are no different from not passing --generate-hashes, so pip will have no problem.

It may be the case that a warning is still appropriate, if unnecessary, since hashes were requested, but the current language says "pip install will require the following package to be hashed," which isn't true in this case.

Reproduction (using plumbum since it has no deps):

$ git clone git@github.com:tomerfiliba/plumbum
$ cd plumbum
$ echo '-e .' > requirements.in
$ pip-compile --no-header --generate-hashes requirements.in

# WARNING: pip install will require the following package to be hashed.
# Consider using a hashable URL like https://github.com/jazzband/pip-tools/archive/SOMECOMMIT.zip
-e file:///home/andy/Code/plumbum  # via -r requirements.in
The generated requirements file may be rejected by pip install. See # WARNING lines for details.

[atugushev]

@AndydeCleyre awesome catch! 🎉 That's so tricky. I'll add a test for that case then.

[AndydeCleyre]

The test looks good 👍 . Is it still the plan to change the has_hashes tracking at all, or is this PR just for the test now?

EDIT: If it's the latter, please just update the PR title.

[atugushev]

@AndydeCleyre

Title updated.

[AndydeCleyre]

Perfect, thanks!

[atugushev]

@AndydeCleyre

Thank you for the analysis and for reviewing this!