Prevent plugin dependencies in "omit" from causing already-imported warnings

[AlexCLeduc]

I came across the same bug noted in this comment when using django plugin alongside both source/include and omit would cause a bunch of already-imported warnings for the plugin's dependencies:

Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/__init__.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/engine.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/base.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/context.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/exceptions.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/library.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/utils.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/defaulttags.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/defaultfilters.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/template/smartif.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/templatetags/__init__.py (already-imported)
Coverage.py warning: Already imported a file that will be measured: .../venv/lib/python3.7/site-packages/django/templatetags/i18n.py (already-imported)

I tried to fix this from the plugin side, but the only place the plugin gets an opinion is in the plugin's file_tracer() method, and we can't disable tracing for the core django templates, otherwise we can't trace the templates themselves.

Every other omit_match check is used too late, after plugins have already imported their dependencies

[codecov-io]

Codecov Report

Merging #1044 into master will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1044      +/-   ##
==========================================
- Coverage   93.97%   93.95%   -0.03%     
==========================================
  Files         179      179              
  Lines       25140    25164      +24     
  Branches     2613     2615       +2     
==========================================
+ Hits        23626    23642      +16     
- Misses       1210     1218       +8     
  Partials      304      304              

Impacted Files	Coverage Δ
coverage/inorout.py	74.07% <100.00%> (+0.29%)	⬆️
tests/test_plugins.py	99.25% <100.00%> (+0.01%)	⬆️
tests/test_debug.py	90.82% <0.00%> (-7.34%)	⬇️
test_plugins.py	98.76% <0.00%> (+0.02%)	⬆️
inorout.py	70.37% <0.00%> (+0.33%)	⬆️

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[nedbat]

Sorry, this has taken a while to get to. Thanks for providing a test! But I tried running the test without your fix, and it didn't fail. Does it fail for you?

[AlexCLeduc]

Sorry about that, I was probably blindly chasing coverage 😄

I've added a new failing test case, you can see it fail with the already-imported warning in CI https://github.com/nedbat/coveragepy/runs/1851303652#step:7:108

[nedbat]

Ugh, I'm sorry, I forgot you had fixed this problem. I fixed it in a different way for #1150. Does it solve the problem for you?

[ProsperousHeart]

Since there has been no response, are we good to close this?

[AlexCLeduc]

Apologies for keeping this open, if I recall correctly I think I had found a different workaround by changing which options I was using and forgot to test the new fix. I'll close now