def test_linear_trend_timewise_days(self):
        """Test linear_trend_timewise function with day intervals."""
        # Try with different days
        x = pd.Series(
            [0, 24, 48, 72],
            index=pd.DatetimeIndex(
                [
                    "2018-01-01 04:00:00",
                    "2018-01-02 04:00:00",
                    "2018-01-03 04:00:00",
                    "2018-01-04 04:00:00",
                ]
            ),
        )

        param = [
            {"attr": "pvalue"},
            {"attr": "rvalue"},
            {"attr": "intercept"},
            {"attr": "slope"},
            {"attr": "stderr"},
        ]
        res = linear_trend_timewise(x, param)

        res = pd.Series(dict(res))

        self.assertAlmostEqual(res['attr_"pvalue"'], 0, places=3)
        self.assertAlmostEqual(res['attr_"stderr"'], 0, places=3)
        self.assertAlmostEqual(res['attr_"intercept"'], 0, places=3)
        self.assertAlmostEqual(res['attr_"slope"'], 1.0, places=3)