Create setup_test_with_server hook

[bernardolins]

Add a hook to be executed before each test_with_server just after the server started.

defmodule MyApp.MyModuleTest do
  use ExUnit.Case
  import FakeServer

  def setup_test_with_server(env) do
    IO.puts "This server is running at port #{env.port}"
  end

  describe "my test describe" do
    # ...
end

[fcapovilla]

I'll work on this issue.