Add unit test
Add unit test

This test runs only when using the TEST_READ_HUGE_FILE env var, as for
the other test_read_big_table test.

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