Hello!

My team has recently switched to Elixir 1.15, but we are facing issues with hiding logs in tests.

Previously, we used to pass the capture_log: true option to ExUnit.start in the test_helper.exs:

ExUnit.start(capture_log: true)

That way we avoid having the console flooded with logs when running our test suite (which contains hundreds of tests), but they are still displayed when a test fails. Since Elixir 1.15 though, we started having some logs leaking despite that option. We noticed that they came from the on_exit handlers, that run in a different process than the main test process.

Following a suggestion from José Valim, I am trying to disable logging for the console instead:

# Configure the general log level. This way logs are produced, captured,
# and displayed whenever a test fails
Logger.configure(level: :debug)

# Configure the console log level to none, so that logs are not displayed while
# running tests
Logger.configure_backend(:console, level: :none)

That works fine, but according to the doc of configure_backend/2: This function is deprecated. Use LoggerBackends.configure/2 from :logger_backends dependency.

But I am struggling to use this new dependency. I could find very little information about it and no example of repository that uses it. I tried to follow what I could understand from the documentation. I tried calling LoggerBackends.configure(LoggerBackends.Console, level: :none) but I get:

** (exit) exited in: :gen_event.call(LoggerBackends, LoggerBackends.Console, {:configure, [level: :none]})
    ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started
    (stdlib 5.1) gen_event.erl:469: :gen_event.call1/3
    test/test_helper.exs:1: (file)

Am I missing something? Would anyone have more information about how to use LoggerBackends?