run a command before running specs, useful for compiling javascript templates

Gemfile

@@ -6,3 +6,4 @@ gem 'guard'
 gem 'rspec'
 gem 'mocha'
 gem 'rake', '0.8.7'
+gem 'growl'

README.md

@@ -14,7 +14,10 @@ home folder's `.jasmine-headless-webkit` file.
 
 ## `guard` options
 
-* `:all_on_start => false` to not run everything when starting, just like `guard-rspec`
+* `:all_on_start => false` to not run everything when starting, just like `guard-rspec`.
+* `:run_before => "<command to run>` to run a command before running specs. If the command fails, the test run stops. Useful for running Jammit before running your specs to compile templates:
+
+  `guard 'jasmine-headliness-webkit', :run_before => 'jammit -f 2>/dev/null' do`
 
 ## What's the deal with `newest_js_file`?
 

lib/guard/jasmine-headless-webkit.rb

@@ -7,21 +7,35 @@ module Guard
     def initialize(watchers = [], options = {})
       super
       @options = {
-        :all_on_start => true
+        :all_on_start => true,
+        :run_before => false
       }.merge(options)
     end
-    
+
     def start
       UI.info "Guard::JasmineHeadlessWebkit is running."
       run_all if @options[:all_on_start]
     end
 
     def run_all
-      JasmineHeadlessWebkitRunner.run
+      JasmineHeadlessWebkitRunner.run if run_before
     end
 
     def run_on_change(paths)
-      run_all if JasmineHeadlessWebkitRunner.run(paths) == 0
+      if run_before
+        run_all if JasmineHeadlessWebkitRunner.run(paths) == 0
+      end
+    end
+
+    private
+    def run_before
+      if @options[:run_before]
+        UI.info "Guard::JasmineHeadlessWebkit running #{@options[:run_before]} first..."
+        system @options[:run_before]
+        $?.exitstatus == 0
+      else
+        true
+      end
     end
   end
 

spec/lib/guard/jasmine-headless-webkit_spec.rb

@@ -45,4 +45,30 @@ describe Guard::JasmineHeadlessWebkit do
       end
     end
   end
+
+  context 'with run_before' do
+    context 'with failing command' do
+      before do
+        Guard::JasmineHeadlessWebkitRunner.expects(:run).never
+      end
+
+      let(:options) { { :run_before => 'false' } }
+
+      it "should run the command first" do
+        guard.run_all
+      end
+    end
+
+    context 'with succeeding command' do
+      before do
+        Guard::JasmineHeadlessWebkitRunner.expects(:run).once
+      end
+
+      let(:options) { { :run_before => 'true' } }
+
+      it "should run the command first" do
+        guard.run_all
+      end
+    end
+  end
 end