def METHOD_NAME(self):
    net = op.network.Demo()
    A = op.phase.StandardGas(network=net, species='o2')
    B = op.phase.StandardGas(network=net, species='n2')
    air = op.phase.StandardGasMixture(network=net, components=[A, B])
    air.y(A.name, 0.21)
    air.y(B.name, 0.79)
    # Ensure models are NOT run during init (no point without mol fracs)
    m = air.models.keys()
    for item in m:
        assert item.split('@')[0] not in air.keys()
    # Make sure models run without complaining
    air.regenerate_models()
    # Make sure all models were actually run
    m = air.models.keys()
    for item in m:
        assert item.split('@')[0] in air.keys()
    air.add_model(propname='pore.diffusivity',
                  model=op.models.phase.diffusivity.gas_mixture_ce)