Test for #16726. unittest that ensures datetime is understood (#16744)
Test for #16726. unittest that ensures datetime is understood (#16744)

* Test for #16726. unittest that ensures datetime is understood

* Corrected the test as suggested by @TomAugspurger

* Fixed flake8 errors and warnings

jreback/pandas,zfrenchee/pandas,winklerand/pandas,toobaz/pandas,jorisvandenbossche/pandas,pratapvardhan/pandas,zfrenchee/pandas,kdebrab/pandas,toobaz/pandas,datapythonista/pandas,cbertinato/pandas,MJuddBooth/pandas,cbertinato/pandas,DGrady/pandas,cython-testbed/pandas,pratapvardhan/pandas,Winand/pandas,louispotok/pandas,gfyoung/pandas,Winand/pandas,nmartensen/pandas,TomAugspurger/pandas,jorisvandenbossche/pandas,jreback/pandas,toobaz/pandas,cbertinato/pandas,DGrady/pandas,harisbal/pandas,dsm054/pandas,cython-testbed/pandas,nmartensen/pandas,dsm054/pandas,zfrenchee/pandas,MJuddBooth/pandas,dsm054/pandas,GuessWhoSamFoo/pandas,GuessWhoSamFoo/pandas,TomAugspurger/pandas,GuessWhoSamFoo/pandas,jmmease/pandas,MJuddBooth/pandas,winklerand/pandas,louispotok/pandas,louispotok/pandas,nmartensen/pandas,jmmease/pandas,winklerand/pandas,jreback/pandas,winklerand/pandas,toobaz/pandas,GuessWhoSamFoo/pandas,harisbal/pandas,rs2/pandas,jreback/pandas,TomAugspurger/pandas,amolkahat/pandas,pandas-dev/pandas,louispotok/pandas,MJuddBooth/pandas,pratapvardhan/pandas,jmmease/pandas,cython-testbed/pandas,kdebrab/pandas,dsm054/pandas,kdebrab/pandas,rs2/pandas,toobaz/pandas,amolkahat/pandas,pandas-dev/pandas,zfrenchee/pandas,harisbal/pandas,pandas-dev/pandas,rs2/pandas,dsm054/pandas,kdebrab/pandas,harisbal/pandas,Winand/pandas,Winand/pandas,kdebrab/pandas,amolkahat/pandas,gfyoung/pandas,MJuddBooth/pandas,TomAugspurger/pandas,DGrady/pandas,gfyoung/pandas,datapythonista/pandas,cython-testbed/pandas,gfyoung/pandas,nmartensen/pandas,cython-testbed/pandas,Winand/pandas,harisbal/pandas,nmartensen/pandas,pratapvardhan/pandas,winklerand/pandas,jorisvandenbossche/pandas,jreback/pandas,GuessWhoSamFoo/pandas,rs2/pandas,Winand/pandas,amolkahat/pandas,jmmease/pandas,cbertinato/pandas,zfrenchee/pandas,DGrady/pandas,DGrady/pandas,nmartensen/pandas,pandas-dev/pandas,louispotok/pandas,jorisvandenbossche/pandas,jmmease/pandas,datapythonista/pandas,cbertinato/pandas,DGrady/pandas,amolkahat/pandas,winklerand/pandas,pratapvardhan/pandas,gfyoung/pandas,datapythonista/pandas,jmmease/pandas