improve unit tests
improve unit tests

saimn/astropy,saimn/astropy,lpsinger/astropy,bsipocz/astropy,dhomeier/astropy,AustereCuriosity/astropy,MSeifert04/astropy,kelle/astropy,MSeifert04/astropy,DougBurke/astropy,mhvk/astropy,aleksandr-bakanov/astropy,MSeifert04/astropy,mhvk/astropy,lpsinger/astropy,mhvk/astropy,larrybradley/astropy,StuartLittlefair/astropy,kelle/astropy,stargaser/astropy,StuartLittlefair/astropy,funbaker/astropy,stargaser/astropy,pllim/astropy,saimn/astropy,mhvk/astropy,larrybradley/astropy,StuartLittlefair/astropy,pllim/astropy,funbaker/astropy,AustereCuriosity/astropy,bsipocz/astropy,bsipocz/astropy,kelle/astropy,lpsinger/astropy,lpsinger/astropy,AustereCuriosity/astropy,larrybradley/astropy,MSeifert04/astropy,astropy/astropy,pllim/astropy,astropy/astropy,StuartLittlefair/astropy,AustereCuriosity/astropy,DougBurke/astropy,dhomeier/astropy,AustereCuriosity/astropy,dhomeier/astropy,saimn/astropy,saimn/astropy,aleksandr-bakanov/astropy,stargaser/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,kelle/astropy,kelle/astropy,pllim/astropy,mhvk/astropy,larrybradley/astropy,funbaker/astropy,DougBurke/astropy,bsipocz/astropy,funbaker/astropy,StuartLittlefair/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,stargaser/astropy,astropy/astropy,astropy/astropy,DougBurke/astropy,pllim/astropy,dhomeier/astropy,dhomeier/astropy,astropy/astropy