Hi, guys!
I am in need of custom backend for the logger, which I kind of put together from Ink. Basically, the backend writes the messages in my format to :stdio. Now, I am trying to test it and decided to use ExUnit.CaptureIO. For some reason logged messages are not being captured.
Basically, I do the following in the code:
test "metadata overwrite" do
captures = ExUnit.CaptureIO.capture_io(:stdio, fn ->
Logger.info "test info no traces"
end)
....
end
what I see on the console:
{"timestamp":"2017-12-16T12:39:31.506Z","module":"Elixir.Logger.JSONBackendTest","message":"test info no traces","line":14,"level":"info","erlang_pid":"#PID<0.137.0>","application":"elixir_common"}
but captures variable is “”
What gives?
Here is my logger config:
config :logger,
backends: [Logger.Backend.JSON
config :logger, Logger.Backend.JSON,
level: :info,
metadata: [:pid, :application, :user_id, :line, :module, :id, :trace, :parent]
Anyone has any clues as to what might be going sideways?
I understand that Logger uses gen_event to push log messages to the backend, so it is all an async process and all but for example doing this did not help:
captures = ExUnit.CaptureIO.capture_io(:stdio, fn ->
Logger.info "test info no traces"
Process.sleep(100)
end)
I see that the message now gets printed before the test ends but I still do not have it captured. I also did this:
captures = ExUnit.CaptureIO.capture_io(:stdio, fn ->
Io.puts "test"
end)
and this worked just fine. Looks like group_leader for the Logger and group leader for the test are not the same. And so ExUnit.CaptureIO is not replacing the desired group leader.
