At the risk of terrible necroposting and of stating the obvious: I ran into this same problem and saw that the OP’s last remarks went unanswered. I found a solution, so maybe other googlers are helped by this:
Our test.exs had
config :logger,
level: :warn
and only by setting it to :info I could get my capture_log assertions to capture the relevant logs.
However, it totally polluted the test output. As described, setting the log level to :warn actually removes the :debug and :info level log statements from the compiled code entirely.
Fortunately, there’s a way around this:
# capture all logs...
config :logger,
level: :debug
# ... but show only warnings and up on the console
config :logger, :console,
level: :warn
This works because Logger’s default backend, console, can be separately configured to filter log levels. That way the Logger.info calls etc are not removed from the code, but the console output is still sane.
I found it all to be documented pretty well in the Logger docs btw: https://hexdocs.pm/logger/Logger.html
