RUBY-345 update logging startup message

lib/mongo/connection.rb

@@ -608,8 +608,7 @@ module Mongo
       @logger = opts[:logger] || nil
 
       if @logger
-        @logger.debug("MongoDB logging. Please note that logging negatively impacts performance " +
+        write_logging_startup_message
-        "and should be disabled for high-performance production apps.")
       end
 
       should_connect = opts.fetch(:connect, true)

lib/mongo/repl_set_connection.rb

@@ -543,8 +543,7 @@ module Mongo
       @cleanup_lock = Mutex.new
 
       if @logger
-        @logger.debug("MongoDB logging. Please note that logging negatively impacts performance " +
+        write_logging_startup_message
-        "and should be disabled for high-performance production apps.")
       end
 
       should_connect = opts.fetch(:connect, true)

lib/mongo/util/logging.rb

@@ -1,6 +1,11 @@
 module Mongo
   module Logging
 
+    def write_logging_startup_message
+      log(:warn, "Please note that logging negatively impacts client-side performance. " +
+      "You should set your logging level no lower than :info in production.")
+    end
+
     # Log a message with the given level.
     def log(level, msg)
       return unless @logger

test/unit/collection_test.rb

@@ -5,7 +5,7 @@ class CollectionTest < Test::Unit::TestCase
   context "Basic operations: " do
     setup do
       @logger = mock()
-      @logger.expects(:debug)
+      @logger.expects(:warn)
     end
 
     should "send update message" do