eunit couch_log_config_test failed with get_listener() found

[wohali]

Current & Expected Behaviour

Sometimes, the couch_log_config_listener_test test couch_log_config_test_ fails. It should always pass

Makefile output:

module 'couch_log_config_listener_test'
  couch_log_config_listener_test: couch_log_config_test_...*failed*
in function couch_log_config_listener_test:'-check_restart_listener/0-fun-2-'/1 (test/couch_log_config_listener_test.erl, line 38)
in call from couch_log_config_listener_test:check_restart_listener/0 (test/couch_log_config_listener_test.erl, line 38)
**error:{assertEqual_failed,[{module,couch_log_config_listener_test},
                     {line,38},
                     {expression,"get_handler ( )"},
                     {expected,not_found},
                     {value,{config_listener,{couch_log_sup,<0.3334.0>}}}]}

  couch_log_config_listener_test: couch_log_config_test_...[1.002 s] ok
  [done in 1.008 s]

couch.log from the uploader is EMPTY.

Possible Solution

Looks like this test is expecting gen_event:delete_handler to occur immediately. Should there be a timer:sleep() call prior to checking get_handler()?

Context

This used to be known as https://issues.apache.org/jira/browse/COUCHDB-3341 but is now on GH Issues.

[eiri]

Just a note: it turned out there could be two causes for this failure 1) we are indeed checking event manager before it had chance to remove old handler 2) couch_log_sup is super fast and spawns and register new handler before we are pulling which_handlers/1, so we are getting new handler. Just sleep would help in half of the cases, so I ended with something a bit more verbose. Hope it'll work more reliably.