def METHOD_NAME(unsupported_nrn_model):
    """
    Test that illegal ``diffusion_connection`` connections raise an exception.
    """
    supported_nrn = nest.Create("siegert_neuron")
    unsupported_nrn = nest.Create(unsupported_nrn_model)
    with pytest.raises(nest.kernel.NESTErrors.IllegalConnection):
        nest.Connect(
            supported_nrn,
            unsupported_nrn,
            conn_spec={"rule": "one_to_one"},
            syn_spec={"synapse_model": "diffusion_connection"},
        )