diff --git a/.gitignore b/.gitignore
index 6ec1a08..fece6cb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,5 +6,4 @@ matter-doc-theme
 build/matter-dev.js
 build/matter-dev.min.js
 demo/js/lib/matter-dev.js
-tests/browser/diffs
-tests/browser/worlds
\ No newline at end of file
+tests/browser/diffs
\ No newline at end of file
diff --git a/.travis.yml b/.travis.yml
index 4f411ab..422054b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,4 +3,5 @@ node_js:
   - "0.10"
 before_install: npm install -g grunt-cli
 install: npm install
-before_script: grunt
\ No newline at end of file
+before_script: 
+	- grunt dev
\ No newline at end of file
diff --git a/Gruntfile.js b/Gruntfile.js
index 7b38f99..a22fee6 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -109,8 +109,11 @@ module.exports = function(grunt) {
       }
     },
     shell: {
-      testBrowser: {
-        command: 'phantomjs tests/browser/TestDemo.js',
+      testDemo: {
+        command: function(arg) {
+          arg = arg ? ' --' + arg : '';
+          return 'phantomjs tests/browser/TestDemo.js' + arg;
+        },
         options: {
           execOptions: {
             timeout: 1000 * 60
@@ -131,10 +134,22 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('grunt-shell');
 
   grunt.registerTask('default', ['test', 'build']);
-  grunt.registerTask('test', ['jshint']);
-  grunt.registerTask('testBrowser', ['shell:testBrowser']);
+  grunt.registerTask('test', ['jshint', 'testDemo']);
   grunt.registerTask('dev', ['build:dev', 'connect:watch', 'watch']);
 
+  grunt.registerTask('testDemo', function() {
+    var updateAll = grunt.option('updateAll'),
+        diff = grunt.option('diff');
+
+    if (updateAll) {
+      grunt.task.run('shell:testDemo:updateAll');
+    } else if (diff) {
+      grunt.task.run('shell:testDemo:diff');
+    } else {
+      grunt.task.run('shell:testDemo');
+    }
+  });
+
   grunt.registerTask('build', function(mode) {
     var isDev = (mode === 'dev'),
         isRelease = (mode === 'release'),
diff --git a/demo/js/Demo.js b/demo/js/Demo.js
index 8e75d60..00304ed 100644
--- a/demo/js/Demo.js
+++ b/demo/js/Demo.js
@@ -25,6 +25,7 @@
     }
 
     var Demo = {};
+    Matter.Demo = Demo;
 
     var _engine,
         _gui,
@@ -34,8 +35,6 @@
         _sceneEvents = [],
         _useInspector = window.location.hash.indexOf('-inspect') !== -1,
         _isMobile = /(ipad|iphone|ipod|android)/gi.test(navigator.userAgent);
-
-    window.Matter.Demo = Demo;
     
     // initialise the demo
 
@@ -53,7 +52,6 @@
         // create a Matter engine
         // NOTE: this is actually Matter.Engine.create(), see the aliases at top of this file
         _engine = Engine.create(container, options);
-        window.Matter.Demo._engine = _engine;
 
         // add a mouse controlled constraint
         _mouseConstraint = MouseConstraint.create(_engine);
@@ -1611,6 +1609,9 @@
         var demoSelect = document.getElementById('demo-select'),
             demoReset = document.getElementById('demo-reset');
 
+        // engine reference for external use
+        Matter.Demo._engine = _engine;
+
         // create a Matter.Gui
         if (!_isMobile && Gui) {
             _gui = Gui.create(_engine);
diff --git a/tests/browser/TestDemo.js b/tests/browser/TestDemo.js
index 1f70c54..3a2dd02 100644
--- a/tests/browser/TestDemo.js
+++ b/tests/browser/TestDemo.js
@@ -53,6 +53,9 @@ var test = function(status) {
         var worldStart = page.evaluate(function(demo) {
             var engine = Matter.Demo._engine;
             Matter.Runner.stop(engine);
+            if (!(demo in Matter.Demo)) {
+                throw '\'' + demo + '\' is not defined in Matter.Demo';
+            }
             Matter.Demo[demo]();
             return engine.world;
         }, demo);
@@ -71,7 +74,7 @@ var test = function(status) {
 
         if (fs.exists(worldStartPath)) {
             var worldStartRef = resurrect.resurrect(fs.read(worldStartPath));
-            var worldStartDiff = compare(worldStart, worldStartRef);
+            var worldStartDiff = compare(worldStartRef, worldStart);
 
             if (worldStartDiff.length !== 0) {
                 if (diff) {
@@ -92,7 +95,7 @@ var test = function(status) {
 
         if (fs.exists(worldEndPath)) {
             var worldEndRef = resurrect.resurrect(fs.read(worldEndPath));
-            var worldEndDiff = compare(worldEnd, worldEndRef);
+            var worldEndDiff = compare(worldEndRef, worldEnd);
 
             if (worldEndDiff.length !== 0) {
                 if (diff) {
@@ -133,9 +136,9 @@ var test = function(status) {
     if (isOk) {
         console.log('ok');
     } else {
-        console.log('changes detected on:');
+        console.log('\nchanges detected on:');
         console.log(changed.join(', '));
-        console.log('review, then --update [name] or --updateAll');
+        console.log('\nreview, then --update [name] or --updateAll');
         console.log('use --diff for diff log');
     }