add unit tests
add unit tests

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