REF/TST: Add more pytest idiom to resample/test_base.py

[simonjayhawkins]

• [ n/a] xref TST/MAINT: split up test_resample.py to make it more understandable #17806
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• [ n/a] whatsnew entry

in this pass:

• restructure fixtures in order to parametrize base class tests
• remove test base class

[pep8speaks]

Hello @simonjayhawkins! Thanks for submitting the PR.

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

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

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

[codecov]

Codecov Report

Merging #24324 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24324   +/-   ##
=======================================
  Coverage   92.28%   92.28%           
=======================================
  Files         162      162           
  Lines       51831    51831           
=======================================
  Hits        47833    47833           
  Misses       3998     3998

Flag	Coverage Δ
#multiple	90.69% <ø> (ø)	⬆️
#single	43% <ø> (ø)	⬆️

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[codecov]

Codecov Report

Merging #24324 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #24324      +/-   ##
==========================================
- Coverage   92.28%   92.28%   -0.01%     
==========================================
  Files         162      162              
  Lines       51831    51831              
==========================================
- Hits        47833    47832       -1     
- Misses       3998     3999       +1

Flag	Coverage Δ
#multiple	90.69% <ø> (ø)	⬆️
#single	43.01% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/testing.py	87.48% <0%> (-0.1%)	⬇️

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[jreback]

let me have a look locally

[simonjayhawkins]

i'm not happy with the restructuring of the fixtures. trying a different approach.