def test_concatenate_dim_time(self):
        """
        Test concatenation with static covariates along time dimension (axis=0)
        Along time dimension, we only take the static covariates of the first series (as static covariates are
        time-independant).
        """
        static_covs_left = pd.DataFrame([[0, 1]], columns=["st1", "st2"]).astype(int)
        static_covs_right = pd.DataFrame([[3, 4]], columns=["st3", "st4"]).astype(int)

        ts_left = linear_timeseries(length=10).with_static_covariates(static_covs_left)
        ts_right = linear_timeseries(
            length=10, start=ts_left.end_time() + ts_left.freq
        ).with_static_covariates(static_covs_right)

        ts_concat = concatenate([ts_left, ts_right], axis=0)
        assert ts_concat.static_covariates.equals(ts_left.static_covariates)

        Test concatenation with static covariates along time dimension (axis=0)
        Along time dimension, we only take the static covariates of the first series (as static covariates are
        time-independant).
        
darts/tests/test_timeseries_static_covariates.py