TST: Regression testing for fixed issues
- [x] closes #10863
- [x] closes #9687
- [x] closes #10078
- [x] closes #8870
- [x] closes #9790
- [x] closes #9892
- [x] closes #10586
- [x] closes #10984
- [x] closes #9149
- [x] closes #9186
- [x] closes #10326
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
