rework logger setup

* CommonLogger by Sinatra is no longer added if
  Rack::Server will add it. Fixes #380.

* Setting the logger options to nil will avoid
  automatically pulling in Rack::NullLogger, thus
  allowing you to set up your own logging
  middleware outside of the Sinatra middleware
  stack. Fixes #371.

README.rdoc

@@ -890,6 +890,11 @@ enable it yourself:
     end
   end
 
+To avoid any logging middleware to be set up, set the +logging+ setting to
++nil+. However, keep in mind that +logger+ will in that case return +nil+. A
+common use case is when you want to set your own logger. Sinatra will use
+whatever it will find in <tt>env['rack.logger']</tt>.
+
 === Mime Types
 
 When using <tt>send_file</tt> or static files you may have mime types Sinatra

lib/sinatra/base.rb

@@ -1353,14 +1353,27 @@ module Sinatra
 
       def setup_logging(builder)
         if logging?
-          builder.use Rack::CommonLogger
-          if logging.respond_to? :to_int
-            builder.use Rack::Logger, logging
-          else
-            builder.use Rack::Logger
-          end
+          setup_common_logger(builder)
+          setup_custom_logger(builder)
+        elsif logging == false
+          setup_null_logger(builder)
+        end
+      end
+
+      def setup_null_logger(builder)
+        builder.use Rack::NullLogger
+      end
+
+      def setup_common_logger(builder)
+        return if ["development", "deployment", nil].include? ENV["RACK_ENV"]
+        builder.use Rack::CommonLogger
+      end
+
+      def setup_custom_logger(builder)
+        if logging.respond_to? :to_int
+          builder.use Rack::Logger, logging
         else
-          builder.use Rack::NullLogger
+          builder.use Rack::Logger
         end
       end
 

test/helpers_test.rb

@@ -1711,6 +1711,16 @@ class HelpersTest < Test::Unit::TestCase
       assert !io.string.include?("INFO -- : Program started")
       assert !io.string.include?("WARN -- : Nothing to do")
     end
+
+    it 'does not create a logger when logging is set to nil' do
+      mock_app do
+        disable :logging
+        get('/') { logger.inspect }
+      end
+
+      get '/'
+      assert_body 'nil'
+    end
   end
 
   module ::HelperOne; def one; '1'; end; end