added more tests
added more tests

abinashpanda/pgmpy,pgmpy/pgmpy,abinashpanda/pgmpy,pgmpy/pgmpy,sandeepkrjha/pgmpy,khalibartan/pgmpy,sandeepkrjha/pgmpy,ankurankan/pgmpy,anaviltripathi/pgmpy,ankurankan/pgmpy,jhonatanoliveira/pgmpy,anaviltripathi/pgmpy,kris-singh/pgmpy,khalibartan/pgmpy,kris-singh/pgmpy,jhonatanoliveira/pgmpy