TST: Test named aggregations with functions
Closes https://github.com/pandas-dev/pandas/issues/28467

Hello @gfyoung! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2019-10-29 06:55:20 UTC thanks @gfyoung 