'gh-2031
Check if it can calculate chi square when there are no attributes which suppose to be.'

def test_chisquare(self):

    a = DiscreteVariable('a', values=['y', 'n'])
    b = DiscreteVariable('b', values=['y', 'n', 'o'])
    table = Table(Domain([a, b]), list(zip('yynny', 'ynyyn')))
    chi = ChiSqStats(table, 0, 1)
    self.assertFalse(isnan(chi.chisq))
