Can I stop swoosh test adapter from sending a message to self()?

Questions / Help
,
1

Swoosh is mucking with a few of my tests. It looks like there is no configurability in the test adapter to change the behavior and get it to stop sending messages. Is there an alternative test adapter that people are using? Maybe the Logger adapter?

It would seem like a silly solution to implement a handle_info catch-all in my LiveView just to make the tests pass.

defmodule Swoosh.Adapters.Test do
  @moduledoc ~S"""
  An adapter that sends emails as messages to the current process.

  This is meant to be used during tests and works with the assertions found in
  the [Swoosh.TestAssertions](Swoosh.TestAssertions.html) module.

  ## Example

      # config/test.exs
      config :sample, Sample.Mailer,
        adapter: Swoosh.Adapters.Test

      # lib/sample/mailer.ex
      defmodule Sample.Mailer do
        use Swoosh.Mailer, otp_app: :sample
      end
  """

  use Swoosh.Adapter

  def deliver(email, _config) do
    for pid <- pids() do
      send(pid, {:email, email})
    end

    {:ok, %{}}
  end

  def deliver_many(emails, _config) do
    for pid <- pids() do
      send(pid, {:emails, emails})
    end

    responses = for _email <- emails, do: %{}

    {:ok, responses}
  end

  # Essentially finds all of the processes that tried to send an email (in the test)
  # and sends an email to that process.
  defp pids do
    if pid = Application.get_env(:swoosh, :shared_test_process) do
      [pid]
    else
      Enum.uniq([self() | List.wrap(Process.get(:"$callers"))])
    end
  end
end
2

Yes and no … Even if you cannot stop some process from sending any messages to self() then you can “silence” such messages by ensuring that self() is not a current test process. Consider simple example:

defmodule Example do
  def sample1 do
    send(self(), :ok)
    notify(1)
  end

  def sample2 do
    spawn(fn -> send(self(), :ok) end)
    notify(2)
  end

  defp notify(step) do
    receive do
      :ok -> IO.puts("[#{step}/2] Received :ok")
    after
      1000 -> IO.puts("[#{step}/2] No message received")
    end
  end
end

Example.sample1()
Example.sample2()

When running this code using elixir example.exs we would got such result:

[1/2] Received :ok
[2/2] No message received

However if you have to send to self() only your messages then it’s also very easy to do, see:

defmodule Example do
  def sample1 do
    send(self(), "ok")
    notify(1)
  end

  def sample2 do
    parent_pid = self()

    spawn(fn ->
      send(self(), "example message from library")
      send(parent_pid, "custom message")
    end)

    notify(2)
  end

  defp notify(step) do
    receive do
      message -> IO.puts("[#{step}/2] Received: #{message}")
    after
      1000 -> IO.puts("[#{step}/2] No message received")
    end
  end
end

Example.sample1()
Example.sample2()

After such changes here is what we’ve got in console:

[1/2] Received: ok
[2/2] Received: custom message