ream88
Ensuring no process crashes when running ExUnit
Hey,
I’m currently writing integration tests for a large Phoenix app. The app involves multiple processes communicating with each other. During the integration tests, I discovered a bug. However, the test run was still reported as successful because the application supervisor restarted the crashing process. I want to ensure that no processes crash during my tests. I have tried several approaches, including using the new :auto_shutdown option from Elixir 1.15, setting :max_restarts in the test environment, and implementing a custom monitor to track all processes globally using :erlang.trace_pattern. Is there a native way to achieve this? While I understand the importance of fixing the bug and writing a unit test, I’m also looking for ways to prevent crashes in the first place.
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al2o3cr
If a tree falls in the forest a process crashes during a spec run but nobody notices, did it really crash?
One way I’ve seen this manifest is code in a spec that GenServer.casts a message but doesn’t assert on any of the resulting side-effects. The fix could be to use :sys.get_state(target_pid) after the cast, which will do two things:
- wait for the
castto be handled and the target GenServer to check its mailbox - ensure that
target_pidis still running
Just getting the state is sufficient for that purpose, but you could also assert further that whatever the cast was supposed to do actually changed in the process’s state.
hubertlepicki
If the crash is logged to the stderr, I’d try using capture_log and seeing there were 0 error logs during the run of my tests… it wouldn’t catch the crashes that could happen in between the tests, but maybe it’s good enough?
hubertlepicki
LOL I’m a bot
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