Added a watch subcommand. Watching a project can now by done with: compass watch

features/command_line.feature

@@ -144,3 +144,13 @@ Feature: Command Line
     And a sass file sass/print.sass is reported unchanged
     And a sass file sass/reset.sass is reported unchanged
     And a sass file sass/utilities.sass is reported unchanged
+
+  Scenario: Watching a project for changes
+    Given I am using the existing project in test/fixtures/stylesheets/compass
+    When I run: compass compile
+    And I run in a separate process: compass watch 
+    And I wait 1 second
+    And I touch sass/layout.sass
+    And I wait 2 seconds
+    And I shutdown the other process
+    And a css file tmp/layout.css is reported identical

features/env.rb

@@ -0,0 +1,35 @@
+require 'cucumber/ast/step_invocation'
+
+module Cucumber
+  module Ast
+    class StepInvocation #:nodoc:
+      def invoke(step_mother, options)
+        find_step_match!(step_mother)
+        unless @skip_invoke || options[:dry_run] || @exception || @step_collection.exception
+          @skip_invoke = true
+          begin
+            @step_match.invoke(@multiline_arg)
+            step_mother.after_step
+            status!(:passed)
+          rescue Pending => e
+            failed(options, e, false)
+            status!(:pending)
+          rescue Undefined => e
+            failed(options, e, false)
+            status!(:undefined)
+          rescue Cucumber::Ast::Table::Different => e
+            @different_table = e.table
+            failed(options, e, false)
+            status!(:failed)
+          rescue SystemExit => e
+            raise
+          rescue Exception => e
+            failed(options, e, false)
+            status!(:failed)
+          end
+        end
+      end
+    end
+  end
+end
+

features/step_definitions/command_line_steps.rb

@@ -42,6 +42,35 @@ When /^I run: compass ([^\s]+) ?(.+)?$/ do |command, args|
   compass command, *(args || '').split
 end
 
+When /^I run in a separate process: compass ([^\s]+) ?(.+)?$/ do |command, args|
+  unless @other_process = fork 
+    @last_result = ''
+    @last_error = ''
+    Signal.trap("HUP") do
+      open('/tmp/last_result.compass_test.txt', 'w') do |file|
+        file.puts $stdout.string
+      end
+      open('/tmp/last_error.compass_test.txt', 'w') do |file|
+        file.puts @stderr.string
+      end
+      exit # This doesn't exit
+    end
+    # this command will run forever
+    # we kill it with a HUP signal from the parent process.
+    args = (args || '').split
+    args << { :wait => 5 }
+    compass command, *args
+    exit
+  end
+end
+
+When /^I shutdown the other process$/ do
+  Process.kill("HUP", @other_process)
+  Process.wait
+  @last_result = File.read('/tmp/last_result.compass_test.txt')
+  @last_error = File.read('/tmp/last_error.compass_test.txt')
+end
+
 When /^I touch ([^\s]+)$/ do |filename|
   FileUtils.touch filename
 end

lib/compass/commands/watch_project.rb

@@ -7,6 +7,8 @@ module Compass
   module Commands
     class WatchProject < UpdateProject
 
+      register :watch
+
       attr_accessor :last_update_time, :last_sass_files
 
       def perform