def test_zero_cardinality_multi_series(self):
        """Check that inverse-transform works as expected when OneHotEncoder is used on several series with
        identical static covariates categories and values.
        """
        ts1 = self.series.with_static_covariates(
            pd.Series({
                "cov_a": "foo",
                "cov_b": "foo",
                "cov_c": "foo",
            })
        )
        ts2 = self.series.with_static_covariates(
            pd.Series({
                "cov_a": "foo",
                "cov_b": "foo",
                "cov_c": "bar",
            })
        )

        transformer = StaticCovariatesTransformer(transformer_cat=OneHotEncoder())
        transformer.fit([ts1, ts2])
        ts1_enc, ts2_enc = transformer.transform([ts1, ts2])
        ts1_inv, ts2_inv = transformer.inverse_transform([ts1_enc, ts2_enc])
        pd.testing.assert_frame_equal(ts1_inv.static_covariates, ts1.static_covariates)
        pd.testing.assert_frame_equal(ts2_inv.static_covariates, ts2.static_covariates)
Check that inverse-transform works as expected when OneHotEncoder is used on several series with
        identical static covariates categories and values.
        
darts/tests/dataprocessing/transformers/test_static_covariates_transformer.py