def test_nunique(self):
        def test_impl(n):
            df = pd.DataFrame({'A': np.arange(n)})
            df.A[2] = 0
            return df.A.nunique()

        hpat_func = self.jit(test_impl)
        n = 1001
        np.testing.assert_almost_equal(hpat_func(n), test_impl(n))
        # test compile again for overload related issues
        hpat_func = self.jit(test_impl)
        np.testing.assert_almost_equal(hpat_func(n), test_impl(n))