'If channel layer provides TEST_CONFIG, `make_test_backend` should
return channel layer instance appropriate for testing.'

@override_settings(CHANNEL_LAYERS={'default': {'BACKEND': 'asgiref.inmemory.ChannelLayer', 'ROUTING': [], 'TEST_CONFIG': {'expiry': 100500}}})
def test_config_instance(self):

    layer = channel_layers.make_test_backend(DEFAULT_CHANNEL_LAYER)
    self.assertEqual(layer.channel_layer.expiry, 100500)
