Ensure log configuration triggers a restart

Author: José Valim

lib/logger/lib/logger.ex

@@ -144,7 +144,7 @@ defmodule Logger do
   The supported keys in the `:colors` keyword list are:
 
     * `:enabled` - boolean value that allows for switching the
-    coloring on and off. Defaults to: `false`
+      coloring on and off. Defaults to: `false`
 
     * `:debug` - color for debug messages. Defaults to: `:magenta`
 

lib/logger/lib/logger/backends/console.ex

@@ -45,12 +45,10 @@ defmodule Logger.Backends.Console do
   end
 
   defp configure_merge(env, options) do
-    env_colors = Keyword.get(env, :colors, [])
-    opts_colors = Keyword.get(options, :colors, [])
-    colors = Keyword.merge(env_colors, opts_colors)
-
-    Keyword.merge(env, options)
-    |> Keyword.put(:colors, colors)
+    Keyword.merge(env, options, fn
+      :colors, v1, v2 -> Keyword.merge(v1, v2)
+      _, _v1, v2 -> v2
+    end)
   end
 
   defp configure_colors(console) do
@@ -73,8 +71,8 @@ defmodule Logger.Backends.Console do
     Logger.Formatter.format(format, level, msg, ts, Dict.take(md, metadata))
   end
 
-  defp color_event(level, data, %{enabled: enabled} = colors) do
-    IO.ANSI.format([Map.fetch!(colors, level) | data], enabled)
-  end
-
+  defp color_event(level, data, %{enabled: true} = colors), do:
+    [IO.ANSI.format_fragment(Map.fetch!(colors, level), true), data|IO.ANSI.reset]
+  defp color_event(_level, data, %{enabled: false}), do:
+    data
 end

lib/logger/test/logger/backends/console_test.exs

@@ -5,7 +5,7 @@ defmodule Logger.Backends.ConsoleTest do
   setup do
     on_exit fn ->
       :ok = Logger.configure_backend(:console,
-          [format: nil, level: nil, metadata: [], colors: [enabled: false]])
+              [format: nil, level: nil, metadata: [], colors: [enabled: false]])
     end
   end
 

lib/mix/lib/mix/tasks/loadconfig.ex

@@ -27,6 +27,15 @@ defmodule Mix.Tasks.Loadconfig do
   end
 
   defp load(file) do
-    Mix.Config.persist Mix.Config.read! file
+    opts = Mix.Config.read!(file)
+    Mix.Config.persist(opts)
+
+    # In case the Logger was changed, we reload the whole
+    # Logger. This is required because many of Logger config
+    # reflects on its supervision tree. No other application
+    # that is bundled with Elixir requires such reloading.
+    if opts[:logger], do: Logger.Config.restart
+
+    :ok
   end
 end

lib/mix/test/mix/tasks/loadconfig_test.exs

@@ -21,9 +21,13 @@ defmodule Mix.Tasks.LoadconfigTest do
 
     in_fixture "no_mixfile", fn ->
       write_config """
-      [my_app: [key: :project]]
+      [my_app: [key: :project],
+       logger: [level: :error]]
       """
 
+      # Original Logger level
+      assert Logger.level == :debug
+
       assert Application.fetch_env(:my_app, :key) == :error
       Mix.Task.run "loadconfig", []
       assert Application.fetch_env(:my_app, :key) == {:ok, :project}
@@ -32,11 +36,16 @@ defmodule Mix.Tasks.LoadconfigTest do
       :ok = :application.load({:application, :my_app, [vsn: '1.0.0', env: [key: :app]]})
       assert Application.fetch_env(:my_app, :key) == {:ok, :project}
 
+      # Logger is reloaded
+      assert Logger.level == :error
+
       # laodconfig can be called multiple times
       # Later values should have higher precedence
       Mix.Task.run "loadconfig", [fixture_path("configs/good_config.exs")]
       assert Application.fetch_env(:my_app, :key) == {:ok, :value}
     end
+  after
+    Logger.configure(level: :debug)
   end
 
   defp write_config(path \\ "config/config.exs", contents) do