def METHOD_NAME(self, estimator_instance, scenario):
    """Main test function for pairwise transformers on tabular data."""
    trafo_name = type(estimator_instance).__name__
    dist_mat = scenario.run(estimator_instance, method_sequence=["transform"])
    X = scenario.args["transform"]["X"]
    len_X = len(scenario.args["transform"]["X"])
    X2 = scenario.args["transform"].get("X2", X)
    len_X2 = len(X2)
    assert isinstance(
        dist_mat, np.ndarray
    ), f"Shape of matrix returned by transform is wrong for {trafo_name}"
    assert (
        # this is only true as long as fixture are of mtypes where len = n_instances
        # should that change, use check_is_mtype to get n_instances metadata
        dist_mat.shape
        == (len_X, len_X2)
    ), f"Shape of matrix returned by transform is wrong for {trafo_name}"