Allow the logger device to be set.

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Improvements
 
+- Allow the logger device to be set with the `:device` option.
 - Improve `list` and `show` command output. ([@netzpirat][])
 - [#386][] Replace Pry's reset command. ([@envygeeks][])
 
@@ -803,4 +804,4 @@ The Listen integration has been supervised by [@thibaudgg][] and executed by [@M
 [@waldo]: https://github.com/waldo
 [@wereHamster]: https://github.com/wereHamster
 [@yannlugrin]: https://github.com/yannlugrin
-[@zonque]: https://github.com/zonque
+[@zonque]: https://github.com/zonque

README.md

@@ -795,14 +795,16 @@ filter /\.js$/
 
 ### logger
 
-The `logger` method allows you to customize the Guard log output to your needs by specifying one or more options like:
+The `logger` method allows you to customize the [Lumberjack](https://github.com/bdurand/lumberjack) log output to your
+needs by specifying one or more options like:
 
 ```ruby
 logger :level       => :warn,
        :template    => '[:severity - :time - :progname] :message',
        :time_format => 'at %I:%M%p',
        :only        => [:rspec, :jasmine, 'coffeescript'],
-       :except      => :jammit
+       :except      => :jammit,
+       :device      => 'guard.log'
 ```
 
 Log `:level` option must be either `:debug`, `:info`, `:warn` or `:error`. If Guard is started in debug mode, the log
@@ -817,6 +819,9 @@ The `:time_format` option directives are the same as Time#strftime or can be `:m
 The `:only` and `:except` are either a string or a symbol, or an array of strings or symbols that matches the name of
 the Guard plugin name that sends the log message. They cannot be specified at the same time.
 
+By default the logger uses `$stderr` as device, but you can override this by supplying the `:device` option and set
+either an IO stream or a filename.
+
 ### Example
 
 ```ruby

lib/guard/ui.rb

@@ -16,15 +16,15 @@ class << self
       # Get the Guard::UI logger instance
       #
       def logger
-        @logger ||= Lumberjack::Logger.new($stderr, self.options)
+        @logger ||= Lumberjack::Logger.new(self.options[:device], self.options)
       end
 
       # Get the logger options
       #
       # @return [Hash] the logger options
       #
       def options
-        @options ||= { :level => :info, :template => ':time - :severity - :message', :time_format => '%H:%M:%S' }
+        @options ||= { :device => $stderr, :level => :info, :template => ':time - :severity - :message', :time_format => '%H:%M:%S' }
       end
 
       # Set the logger options

spec/guard/ui_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Guard::UI do
-  after { Guard::UI.options = { :level => :info, :template => ':time - :severity - :message', :time_format => '%H:%M:%S' } }
+  after { Guard::UI.options = { :level => :info, :device => $stderr, :template => ':time - :severity - :message', :time_format => '%H:%M:%S' } }
 
   before do
     # The spec helper stubs all UI classes, so other specs doesn't have
@@ -32,6 +32,10 @@
     it 'returns the logger instance' do
       Guard::UI.logger.should be_an_instance_of Lumberjack::Logger
     end
+
+    it 'sets the logger device' do
+      Guard::UI.logger.device.send(:stream).should be $stderr
+    end
   end
 
   describe '.options=' do