Fix the LoggerSilence to work as described:

- Following the Rails guide which state that a logger needs to include
  the `ActiveSupport::LoggerSilence` as well as
  `ActiveSupport::LoggerThreadSafe` modules isn't enough and won't
  work.

  Here is a test cases with 3 tests that all fails
  https://gist.github.com/Edouard-chin/4a72930c2b1eafbbd72a80c66f102010

  The problems are the following:

  1) The logger needs to call `after_initialize` in order to setup
  some instance variables.
  2) The silence doesn't actually work because the bare ruby Logger
  `add` method checks for the instance variable `@logger`. We need to
  override the `add` (like we used to in the ActiveSupport::Logger
  class).
  3) Calling `debug?` `info?` etc... doesn't work as the bare ruby
  methods will check for the instance variable. Again we need to
  override this methods (like we used to in the ActiveSupport::Logger
  class)

  The LoggerSilence won't work without LoggerThreadSafe, but the later
  is not public API, the user shouldn't have to include it so I
  modified to include it automatically.
  Same for the `after_initialize` method. I find unuintitive to have
  to call it directly. I modified to instance the variables when the
  module get included.

1 files changed, 2 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/logger_silence.rb b/activesupport/lib/active_support/logger_silence.rb
index 2f62cc13b9..b2444c1e34 100644
--- a/activesupport/lib/active_support/logger_silence.rb
+++ b/activesupport/lib/active_support/logger_silence.rb
@@ -2,6 +2,7 @@
 
 require "active_support/concern"
 require "active_support/core_ext/module/attribute_accessors"
+require "active_support/logger_thread_safe_level"
 
 module LoggerSilence
   extend ActiveSupport::Concern
@@ -22,6 +23,7 @@ module ActiveSupport
 
     included do
       cattr_accessor :silencer, default: true
+      include ActiveSupport::LoggerThreadSafeLevel
     end
 
     # Silences the logger for the duration of the block.