Add Logger.flush/0

Author: José Valim

lib/logger/lib/logger.ex

@@ -343,6 +343,20 @@ defmodule Logger do
     Logger.Config.configure(Dict.take(options, @valid_options))
   end
 
+  @doc """
+  Flushes the Logger.
+
+  This basically guarantees all messages sent to the
+  Logger prior to this call will be processed. This is useful
+  for testing and it should not be called in production code.
+  """
+  @spec flush :: :ok
+  def flush do
+    _ = GenEvent.which_handlers(:error_logger)
+    _ = GenEvent.which_handlers(Logger)
+    :ok
+  end
+
   @doc """
   Adds a new backend.
 

lib/logger/test/test_helper.exs

@@ -39,8 +39,7 @@ defmodule Logger.Case do
     Logger.configure(level: level)
     capture_io(:user, fn ->
       fun.()
-      GenEvent.which_handlers(:error_logger)
-      GenEvent.which_handlers(Logger)
+      Logger.flush()
     end)
   after
     Logger.configure(level: :debug)