TST: add test for case when null in expected column
TST: add test for case when null in expected column

umuzungu/zipline,alphaBenj/zipline,humdings/zipline,Scapogo/zipline,umuzungu/zipline,bartosh/zipline,humdings/zipline,Scapogo/zipline,enigmampc/catalyst,quantopian/zipline,florentchandelier/zipline,alphaBenj/zipline,florentchandelier/zipline,wilsonkichoi/zipline,bartosh/zipline,magne-max/zipline-ja,quantopian/zipline,magne-max/zipline-ja,wilsonkichoi/zipline,enigmampc/catalyst