[MRG] cleanup and commenting of test_index.py tests.

[ctb]

Note: PR into #1891. Review & merge after that one.

This PR does some cleanup and commenting on tests/test_index.py, as well as pyflakes-based cleaning of src/sourmash/index/__init__.py.

This is a pure commenting-and-docstring PR, no code changes.

[codecov]

Codecov Report

Merging #1898 (841ebf1) into latest (f05e4bd) will increase coverage by 7.89%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           latest    #1898      +/-   ##
==========================================
+ Coverage   82.83%   90.73%   +7.89%     
==========================================
  Files         122       92      -30     
  Lines       13257     9052    -4205     
  Branches     1789     1789              
==========================================
- Hits        10981     8213    -2768     
+ Misses       2013      576    -1437     
  Partials      263      263              

Flag	Coverage Δ
python	90.73% <ø> (-0.01%)	⬇️
rust	?

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Impacted Files	Coverage Δ
src/sourmash/index/__init__.py	96.73% <ø> (-0.02%)	⬇️
src/sourmash/index/revindex.py	63.46% <ø> (ø)
src/core/src/sketch/hyperloglog/estimators.rs
src/core/src/ffi/hyperloglog.rs
src/core/src/sketch/hyperloglog/mod.rs
src/core/src/index/revindex.rs
src/core/src/errors.rs
src/core/src/lib.rs
src/core/src/ffi/signature.rs
src/core/src/from.rs
... and 22 more

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[luizirber]

as well as pyflakes-based cleaning

😮 you're using pyflakes?!?!?

[ctb]

as well as pyflakes-based cleaning

😮 you're using pyflakes?!?!?

yes... is that surprising? or bad?

[luizirber]

yes... is that surprising? or bad?

it's great, means that we might finally uncomment flake8 from the pre-commit checks 🙃

(or at least run these things more frequently and reduce the mountain of warnings 🙈 )

[ctb]

yes... is that surprising? or bad?

it's great, means that we might finally uncomment flake8 from the pre-commit checks 🙃

(or at least run these things more frequently and reduce the mountain of warnings 🙈 )

sure - I can make that an issue. It'd be good to do it systematically across the code base; in the tests I have more tolerance for unused variables, but even there flakes found a number of shadowed tests - see #1863.