test: verify listener leak is only emitted once
When a possible listener leak is detected, a warning is emitted. This commit updates an existing test to verify that the warning is only emitted once.
In conjunction with #12501, should bring coverage of lib/events.js
up to 100%.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines
Affected core subsystem(s)
test