Hey everyone,

I have test that check if messages have been sent to a process and to make sure I test against the one I want, I clear out the others. Previously I was using lib.flush_receive/0 but that has since been removed. It looks like c.flush/0 is the replacement. One thing that I dislike about c.flush/0 is that it outputs the messages which makes looking at test failures very tedious. I tried combining the call with ExUnit.CaptureIO.capture_io/1 but I’m getting ArgumentErrors, from seemingly c.flush/0 itself?

Here’s the code I’m using:

   try do
      capture_io(&:c.flush/0)
    rescue
      ArgumentError ->
        IO.puts "Error flushing mailbox!"
        IO.inspect __STACKTRACE__
    end

and the output looks like

Error flushing mailbox!
[
{:lists, :keyfind, [:encoding, 1, {:ok, [binary: true, encoding: :unicode]}],
},
{:c, :flush, 0, [file: ‘c.erl’, line: 819]},
{ExUnit.CaptureIO, :do_capture_io, 2,
[file: ‘lib/ex_unit/capture_io.ex’, line: 151]},
{ExUnit.CaptureIO, :do_capture_io, 3,
[file: ‘lib/ex_unit/capture_io.ex’, line: 121]},
{PlexServer.EmpireChannelUtils, :flush_mailbox, 1,
[file: ‘test/channels/empire_channel_utils.exs’, line: 54]},
{PlexServer.EmpireChannelTest, :“test succesful action: spend invade moves”,
1, [file: ‘test/channels/empire_channel_test.exs’, line: 567]},
{ExUnit.Runner, :exec_test, 1, [file: ‘lib/ex_unit/runner.ex’, line: 355]},
{:timer, :tc, 1, [file: ‘timer.erl’, line: 166]},
{ExUnit.Runner, :“-spawn_test_monitor/4-fun-1-”, 4,
[file: ‘lib/ex_unit/runner.ex’, line: 306]}
]

Digging into the c.flush/0 source, it seems that it calls io.getopts/0 and that’s returning a tuple rather than just an array? Why would this work without the capture_io/1?

Not really sure how to proceed. Any ideas?