When running unit tests for dropped events; how can I disable the stderr message "ERROR transform"?

[patrick-oday-cruise]

I have a unit test that uses a log event that is supposed to:

1. Test a remap transform that specifies reroute_dropped = true and drop_on_abort = true
2. Trigger an abort via parse_linux_authorization!
3. Then capture the dropped event by a downstream dropped handler.

The test works as expected except that it prints out to stderr the details of the dropped event. Is there a way to configure the test so that it's aware that the transform will drop the event and not print to stderr during testing?

The stderr that I'm referring to:

2023-05-04T22:50:10.449577Z ERROR transform{component_kind="transform" component_id=syslog_transform component_type=remap component_name=syslog_transform}: vector::internal_events::remap: Mapping failed with event. error="function call error for "parse_linux_authorization" at (22:58): unable to parse input as valid syslog message" error_type="conversion_failed" stage="processing" internal_log_rate_limit=true
2023-05-04T22:50:10.449702Z ERROR transform{component_kind="transform" component_id=syslog_transform component_type=remap component_name=syslog_transform}: vector_common::internal_event::component_events_dropped: Events dropped intentional=false count=1 reason="Mapping failed with event." internal_log_rate_limit=true

I want to have tests that ensure the messages that should be dropped are correctly dropped. The behavior of parse_key_value wasn't exactly as I had expected but I was unaware until testing the failure states.

[spencergilbert]

I don't believe that's an existing feature - have you tried redirecting STDOUT vs STDERR?

[patrick-oday-cruise]

I have tried redirecting stderr to hide the in-progress intentional errors but I'm concerned that it may also hide other important information, especially when someone is iterating on a test. It's that I'd want stderr messages when a test that is supposed to drop a log event doesn't and stderr messages when a test that isn't supposed to drop a log event does.

[spencergilbert]

Got it, definitely not supported today - please open a feature request issue with the use case and details you provided. Thanks!