I’m using a Context Manager, but how can I mock the behavior of Prefect such that I can only test the setup function? I tried

@pytest.fixture
def mock_resource_manager(monkeypatch):
    mock = MagicMock(return_value=None)
    monkeypatch.setattr("prefect.tasks.core.resource_manager.ResourceManager.__call__", mock)
    return mock

But this gives weird errors down the road, as I also want to mock prefect.config/context for other purposes.

Don't? Wrap your actual logic in a function that pulls from the context and pass into an interior function that is pure and only depends in its args?

Hmm not sure if I understtand you. Let me give some more details, I got this resoure manager of which I want to test the setup function

@resource_manager
class CloudSQLProxyManager:
    def __init__(self, name, instance, keyfile):
        self.instance = instance
        self.keyfile = keyfile
        self.name = name
        self.skip_deployment = prefect.config.get('environment', 'development').lower() != 'production'

    def setup(self):
        if self.skip_deployment:
            <http://prefect.context.logger.info|prefect.context.logger.info>(f"Skipping creation of CloudSQL Proxy")
            raise signals.SUCCESS("Creation of CloudSQL Proxy skipped")
        # ....

I tried your suggestion, without mocking:

`def test__setup__skips_on_non_production(mock_resource_manager):
    prefect.config['environment'] = 'development'

    flow = Flow("unit test")
    manager = CloudSQLProxyManager("name", "instance", "keyfile", flow=flow)
    with pytest.raises(signals.SUCCESS, match="Creation of CloudSQL Proxy skipped"):
        print(manager)
        manager.setup(manager)

But then manager is an instance of ResourceManager (and not CloudSQLLProxyManager) I tried mocking the call (as shown in my initial post), but that makes manager None.