REF/TST: collect reduction tests

[jbrockmendel]

Similar to how to have tests.arithmetic for tests where we expect EA/Index/Series/DataFrame behavior to be analogous, this starts collecting the tests for reduction operations. This is motivated by #24293.

This does not yet collect tests from tests.frame.test_analytics or any of tests.arrays or tests.indexes.

Optionally we may want parts of test_nanops to be part of test_reductions, since those functions will also be in the check-these-are-equivalent pile.

Parametrizes some tests in test_base.

Moved tests are unchanged, except for non-context usages of pytest.raises are context-ified; some tests are parametrized.

[codecov]

Codecov Report

Merging #24367 into master will decrease coverage by 49.3%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master   #24367       +/-   ##
===========================================
- Coverage   92.29%   42.98%   -49.31%     
===========================================
  Files         162      162               
  Lines       51832    51832               
===========================================
- Hits        47839    22281    -25558     
- Misses       3993    29551    +25558

Flag	Coverage Δ
#multiple	?
#single	42.98% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/io/formats/latex.py	0% <0%> (-100%)	⬇️
pandas/core/categorical.py	0% <0%> (-100%)	⬇️
pandas/io/sas/sas_constants.py	0% <0%> (-100%)	⬇️
pandas/tseries/plotting.py	0% <0%> (-100%)	⬇️
pandas/tseries/converter.py	0% <0%> (-100%)	⬇️
pandas/io/formats/html.py	0% <0%> (-98.65%)	⬇️
pandas/core/groupby/categorical.py	0% <0%> (-95.46%)	⬇️
pandas/io/sas/sas7bdat.py	0% <0%> (-91.17%)	⬇️
pandas/io/sas/sas_xport.py	0% <0%> (-90.15%)	⬇️
pandas/core/tools/numeric.py	10.44% <0%> (-89.56%)	⬇️
... and 120 more

---

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[codecov]

Codecov Report

Merging #24367 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24367   +/-   ##
=======================================
  Coverage    92.3%    92.3%           
=======================================
  Files         162      162           
  Lines       51875    51875           
=======================================
  Hits        47883    47883           
  Misses       3992     3992

Flag	Coverage Δ
#multiple	90.71% <ø> (ø)	⬆️
#single	42.99% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[TomAugspurger]

Thoughts on using markers instead of (or in addition to) moving?

[jbrockmendel]

Thoughts on using markers instead of (or in addition to) moving?

The idea is to parametrize in order to make sure we test that behavior matches across the classes. I don't see how using a marker instead gets us closer to that.

[jreback]

does it make sense to make this a subdir to start?

[jbrockmendel]

I'm hopeful this won't be a big enough file to need to be split. Easier to split later than un-split.

[jreback]

its already a pretty hefty file no?

[jbrockmendel]

i guess. will split.

[pep8speaks]

Hello @jbrockmendel! Thanks for updating the PR.

• There are no PEP8 issues in the file pandas/tests/reductions/__init__.py !

• There are no PEP8 issues in the file pandas/tests/reductions/test_reductions.py !

• There are no PEP8 issues in the file pandas/tests/reductions/test_stat_reductions.py !

• There are no PEP8 issues in the file pandas/tests/series/test_analytics.py !

• There are no PEP8 issues in the file pandas/tests/series/test_datetime_values.py !

• There are no PEP8 issues in the file pandas/tests/series/test_operators.py !

• There are no PEP8 issues in the file pandas/tests/series/test_timeseries.py !

• There are no PEP8 issues in the file pandas/tests/test_base.py !

[jreback]

ok, would like to remove the classes and rather have separate files for each. can leave that for a separate pass.