BUG: Ensuring that _get_standard_colors returns num_colors (GH #20585)

[nokutu]

• closes Default behavior of plot.bar changed to plot a different color for each bar #20585
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[jreback]

looks good. can you also add the example from the OP (which was a groupby) and assert that the colors are all the same. pls add a whatsnew note (bug fixes in plotting) as well. ping on green.

[codecov]

Codecov Report

Merging #24504 into master will decrease coverage by 49.25%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##           master   #24504       +/-   ##
===========================================
- Coverage   92.31%   43.05%   -49.26%     
===========================================
  Files         166      166               
  Lines       52391    52392        +1     
===========================================
- Hits        48363    22557    -25806     
- Misses       4028    29835    +25807

Flag	Coverage Δ
#multiple	?
#single	43.05% <0%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/plotting/_style.py	23.4% <0%> (-54.02%)	⬇️
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%)	⬇️
... and 125 more

---

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[codecov]

Codecov Report

Merging #24504 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #24504      +/-   ##
==========================================
- Coverage   31.89%   31.87%   -0.02%     
==========================================
  Files         166      166              
  Lines       52434    52428       -6     
==========================================
- Hits        16722    16714       -8     
- Misses      35712    35714       +2

Flag	Coverage Δ
#multiple	30.28% <0%> (-0.01%)	⬇️
#single	31.87% <0%> (-0.02%)	⬇️

Impacted Files	Coverage Δ
pandas/plotting/_style.py	23.4% <0%> (-0.26%)	⬇️
pandas/plotting/_core.py	18.17% <0%> (ø)	⬆️
pandas/core/internals/blocks.py	38.09% <0%> (-0.4%)	⬇️
pandas/core/indexes/datetimes.py	36.95% <0%> (-0.39%)	⬇️
pandas/core/base.py	26.45% <0%> (-0.37%)	⬇️
pandas/core/indexes/timedeltas.py	42.57% <0%> (-0.29%)	⬇️
pandas/core/indexes/period.py	31.4% <0%> (-0.1%)	⬇️
pandas/io/pytables.py	19.52% <0%> (-0.01%)	⬇️
pandas/core/algorithms.py	31.7% <0%> (ø)	⬆️
pandas/core/generic.py	31.41% <0%> (ø)	⬆️
... and 9 more

---

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[nokutu]

Why is only the azure pipeline failing? Is it because of something changed?

[jreback]

you need to click thru: https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=6152

you have linting errors & the added test fails.

[nokutu]

ping @jreback

[jreback]

FYI: we just merged #20727 which touches similar code. So for sure rebase on master and see if your patch still works.

[jreback]

cc @TomAugspurger

[nokutu]

ping

[jreback]

thanks @nokutu