TST: Add test for groupby mean of ints

[gfyoung]

Title is self-explanatory.

Closes #11199.

[codecov]

Codecov Report

Merging #16670 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #16670   +/-   ##
=======================================
  Coverage   90.93%   90.93%           
=======================================
  Files         161      161           
  Lines       49269    49269           
=======================================
  Hits        44802    44802           
  Misses       4467     4467

Flag	Coverage Δ
#multiple	88.69% <ø> (ø)	⬆️
#single	40.22% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 18a428d...8802f44. Read the comment docs.

[codecov]

Codecov Report

Merging #16670 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #16670   +/-   ##
=======================================
  Coverage   90.93%   90.93%           
=======================================
  Files         161      161           
  Lines       49269    49269           
=======================================
  Hits        44802    44802           
  Misses       4467     4467

Flag	Coverage Δ
#multiple	88.69% <ø> (ø)	⬆️
#single	40.22% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 18a428d...8802f44. Read the comment docs.

[jreback]

lgtm. if you'd have a look at the xref issues (which are closed):

xref #15091
xref #3707

to see if we want to add any tests from those.

[gfyoung]

to see if we want to add any tests from those.

Why not, if possible? 😄 I can add those as separate PR's.

[jreback]

ok then (FYI sometimes I have xref duplicate issues that have potentially other tests). yes a new PR is fine.

[gfyoung]

@jreback : Unfortunately, both issues are still valid on master. They actually were not addressed by the fixing of #11199 as you had imagined. 😢

[jreback]

hmm can u create a new issue with he simplest repro possible for both of those (and cited the old)
there is lots of chatter on those

[gfyoung]

@jreback #3707 has been resurrected as #16674, but with a slightly broader focus.