fearture(logging): Ensure logged messages are formatted correctly

- Ensures logged messages have the correct bugsnag formatting
- Ensures custom loggers receive the formatted message rather than the raw message
- Adds a new public method - 'format_message'

lib/bugsnag/configuration.rb

@@ -88,9 +88,6 @@ def initialize
       # Set up logging
       self.logger = Logger.new(STDOUT)
       self.logger.level = Logger::INFO
-      self.logger.formatter = proc do |severity, datetime, progname, msg|
-        "** [Bugsnag] #{datetime}: #{msg}\n"
-      end
 
       # Configure the bugsnag middleware stack
       self.internal_middleware = Bugsnag::MiddlewareStack.new
@@ -169,19 +166,26 @@ def clear_request_data
     ##
     # Logs an info level message
     def info(message)
-      logger.info(message)
+      logger.info(format_message(message))
     end
 
     ##
     # Logs a warning level message
     def warn(message)
-      logger.warn(message)
+      logger.warn(format_message(message))
     end
 
     ##
     # Logs a debug level message
     def debug(message)
-      logger.debug(message)
+      logger.debug(format_message(message))
+    end
+
+    ##
+    # Formats a message being logged by Bugsnag
+    def format_message(message)
+      datetime = Time.new.to_s
+      "** [Bugsnag] #{datetime}: #{message.to_s}\n"
     end
 
     private

spec/configuration_spec.rb

@@ -29,6 +29,81 @@
     end
   end
 
+  describe "logger" do
+    class TestLogger
+      attr_accessor :logs
+
+      def initialize
+        @logs = []
+      end
+
+      def log(level, message)
+        @logs << {
+          :level => level,
+          :message => message
+        }
+      end
+
+      def info(msg)
+        log('info', msg)
+      end
+
+      def warn(msg)
+        log('warning', msg)
+      end
+
+      def debug(msg)
+        log('debug', msg)
+      end
+    end
+
+    before do
+      @logger = TestLogger.new
+      @string_regex = /\*\* \[Bugsnag\] (\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} (\+\d{4})?): (Info|Warning|Debug) message\n$/
+      Bugsnag.configure do |bugsnag|
+        bugsnag.logger = @logger
+      end
+    end
+
+    it "should format a message correctly" do
+      formatted_msg = /\*\* \[Bugsnag\] (\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} (\+\d{4})?): message\n$/
+      expect(Bugsnag.configuration.format_message("message")).to match(formatted_msg)
+    end
+
+    it "should log info messages to the set logger" do
+      expect(@logger.logs.size).to eq(0)
+      Bugsnag.configuration.info("Info message")
+      expect(@logger.logs.size).to eq(1)
+      log = @logger.logs.first
+      expect(log[:level]).to eq('info')
+      expect(log[:message]).to match(@string_regex)
+    end
+
+    it "should log warning messages to the set logger" do
+      expect(@logger.logs.size).to eq(0)
+      Bugsnag.configuration.warn("Warning message")
+      expect(@logger.logs.size).to eq(1)
+      log = @logger.logs.first
+      expect(log[:level]).to eq('warning')
+      expect(log[:message]).to match(@string_regex)
+    end
+
+    it "should log debug messages to the set logger" do
+      expect(@logger.logs.size).to eq(0)
+      Bugsnag.configuration.debug("Debug message")
+      expect(@logger.logs.size).to eq(1)
+      log = @logger.logs.first
+      expect(log[:level]).to eq('debug')
+      expect(log[:message]).to match(@string_regex)
+    end
+
+    after do
+      Bugsnag.configure do |bugsnag|
+        bugsnag.logger = Logger.new(StringIO.new)
+      end
+    end
+  end
+
   it "should have exit exception classes ignored by default" do
     expect(subject.ignore_classes).to eq(Set.new([SystemExit, Interrupt]))
   end