Added some specs,and some lines in README/CHANGELOG for dry-run option.

And added support for Kernel.#` and %x literal.

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 ## Improvements
 
+- Pull request [#95](https://github.com/guard/guard/pull/95): Do a dry run without executing actions when the `:clear` option is given. ([@uk-ar][])
 - Pull request [#94](https://github.com/guard/guard/pull/94): Show backtrace in terminal when a problem with a watch action occurs. ([@capotej][])
 - Pull request [#88](https://github.com/guard/guard/pull/88): Write exception trace in the terminal when a supervised task fail. ([@mcmire][])
 - Color in red the "ERROR:" flag when using `UI.error`. ([@rymai][])

README.md

@@ -163,6 +163,15 @@ $ guard --debug
 $ guard -d # shortcut
 ```
 
+### `--dry-run` option
+
+Do a dry run without executing actions:
+
+``` bash
+$ guard --dry-run
+$ guard -y # shortcut
+```
+
 An exhaustive list of options is available with:
 
 ``` bash

lib/guard.rb

@@ -19,10 +19,15 @@ module Guard
 
       @options[:notify] && ENV["GUARD_NOTIFY"] != 'false' ? Notifier.turn_on : Notifier.turn_off
 
+      if @options[:"dry-run"]
         Kernel.send(:define_method, :system ) do
-        |program, *args| print program + ' ' + args.join(' ') + "\n"
-      end if options.dry_run
+          |program, *args| Kernel.print program + ' ' + args.join(' ') + "\n"
+        end
 
+        Kernel.send(:define_method, :"`" ) do
+          |command| Kernel.print command + "\n"
+        end
+      end
       self
     end
 

lib/guard/cli.rb

@@ -9,7 +9,7 @@ module Guard
     method_option :notify, :type => :boolean, :default => true,  :aliases => '-n', :banner => "Notifications feature (growl/libnotify)"
     method_option :debug,  :type => :boolean, :default => false, :aliases => '-d', :banner => "Print debug messages"
     method_option :group,  :type => :array,   :default => [],    :aliases => '-g', :banner => "Run only the passed groups"
-    method_option :dry_run,  :type => :boolean, :default => false, :aliases => '-y', :banner => "Do a dry run without executing actions"
+    method_option :"dry-run",  :type => :boolean, :default => false, :aliases => '-y', :banner => "Do a dry run without executing actions"
 
     desc "start", "Starts Guard"
     def start

spec/guard_spec.rb

@@ -39,6 +39,44 @@ describe Guard do
       ::Guard::Notifier.should_receive(:turn_off)
       ::Guard.setup(:notify => true)
     end
+
+    context do
+      before do
+        @original_system = Kernel.method(:system)
+        @original_command = Kernel.method(:"`")
+      end
+
+      after do
+        Kernel.send(:define_method, :system, @original_system.to_proc )
+        Kernel.send(:define_method, :"`", @original_command.to_proc )
+      end
+
+      it "overwrites Kernel.#system method if the dry-run option is false" do
+        ::Guard.setup(:"dry-run" => false)
+        ::Kernel.should_not_receive(:print).with("command arg1 arg2\n")
+        system("command","arg1","arg2")
+      end
+
+      it "overwrites Kernel.#system method if the dry-run option is true" do
+        ::Guard.setup(:"dry-run" => true)
+        ::Kernel.should_receive(:print).with("command arg1 arg2\n")
+        system("command","arg1","arg2")
+      end
+
+      it "overwrites Kernel.#` method if the dry-run option is false" do
+        ::Guard.setup(:"dry-run" => false)
+        ::Kernel.should_not_receive(:print).with("command\n")
+        `command`
+        %x{command}
+      end
+
+      it "overwrites Kernel.#` method if the dry-run option is false" do
+        ::Guard.setup(:"dry-run" => true)
+        ::Kernel.should_receive(:print).twice.with("command\n")
+        `command`
+        %x{command}
+      end
+    end
   end
 
   describe ".get_guard_class" do