add tests in expressions_tests
add tests in expressions_tests

apavlo/peloton,cmu-db/peloton,vittvolt/15721-peloton,ShuxinLin/peloton,AllisonWang/peloton,yingjunwu/peloton,wangziqi2016/peloton,jessesleeping/iso_peloton,vittvolt/peloton,jessesleeping/iso_peloton,haojin2/peloton,seojungmin/peloton,yingjunwu/peloton,ShuxinLin/peloton,seojungmin/peloton,vittvolt/peloton,AllisonWang/peloton,cmu-db/peloton,cmu-db/peloton,haojin2/peloton,wangziqi2016/peloton,ShuxinLin/peloton,PauloAmora/peloton,prashasthip/peloton,eric-haibin-lin/peloton-1,cmu-db/peloton,jessesleeping/iso_peloton,PauloAmora/peloton,AllisonWang/peloton,phisiart/peloton-p3,haojin2/peloton,jessesleeping/iso_peloton,wangziqi2016/peloton,jessesleeping/iso_peloton,haojin2/peloton,AngLi-Leon/peloton,AngLi-Leon/peloton,jessesleeping/iso_peloton,seojungmin/peloton,ShuxinLin/peloton,malin1993ml/peloton,eric-haibin-lin/peloton-1,apavlo/peloton,malin1993ml/peloton,jessesleeping/iso_peloton,AngLi-Leon/peloton,PauloAmora/peloton,seojungmin/peloton,vittvolt/15721-peloton,malin1993ml/peloton,yingjunwu/peloton,haojin2/peloton,seojungmin/peloton,ShuxinLin/peloton,malin1993ml/peloton,PauloAmora/peloton,eric-haibin-lin/peloton-1,AllisonWang/peloton,phisiart/peloton-p3,cmu-db/peloton,vittvolt/peloton,prashasthip/peloton,vittvolt/peloton,AngLi-Leon/peloton,AllisonWang/peloton,yingjunwu/peloton,AllisonWang/peloton,prashasthip/peloton,malin1993ml/peloton,prashasthip/peloton,vittvolt/15721-peloton,phisiart/peloton-p3,cmu-db/peloton,wangziqi2016/peloton,vittvolt/15721-peloton,wangziqi2016/peloton,phisiart/peloton-p3,AngLi-Leon/peloton,apavlo/peloton,seojungmin/peloton,prashasthip/peloton,prashasthip/peloton,malin1993ml/peloton,vittvolt/15721-peloton,PauloAmora/peloton,apavlo/peloton,apavlo/peloton,vittvolt/peloton,PauloAmora/peloton,vittvolt/peloton,yingjunwu/peloton,vittvolt/15721-peloton,apavlo/peloton,yingjunwu/peloton,eric-haibin-lin/peloton-1,haojin2/peloton,AngLi-Leon/peloton,ShuxinLin/peloton,wangziqi2016/peloton,phisiart/peloton-p3,phisiart/peloton-p3,eric-haibin-lin/peloton-1,eric-haibin-lin/peloton-1