fix(ng:class): make ng:class friendly towards other code adding/removing classes

ng:class as well as ng:class-odd and ng:class-even always reset the
class list to whatever it was before compilation, this makes it
impossible to create another directive which adds its own classes on the
element on which ng:class was applied.

the fix simply removes all classes that were added previously by
ng:class and add classes that the ng:class expression evaluates to.

we can now guarantee that we won't clobber stuff added before or after
compilation as long as all class names are unique.

in order to implement this I had to beef up jqLite#addClass and
jqLite#removeClass to be able to add/remove multiple classes without
creating duplicates.

5 files changed, 167 insertions, 37 deletions

diff --git a/src/directives.js b/src/directives.js
index b3584a37..2e1040c0 100644
--- a/src/directives.js
+++ b/src/directives.js
@@ -549,16 +549,11 @@ angularDirective("ng:submit", function(expression, element) {
 
 function ngClass(selector) {
   return function(expression, element) {
-    var existing = element[0].className + ' ';
     return function(element) {
-      this.$watch(function(scope) {
+      this.$watch(expression, function(scope, newVal, oldVal) {
         if (selector(scope.$index)) {
-          var ngClassVal = scope.$eval(element.attr('ng:class'));
-          if (isArray(ngClassVal)) ngClassVal = ngClassVal.join(' ');
-          var value = scope.$eval(expression);
-          if (isArray(value)) value = value.join(' ');
-          if (ngClassVal && ngClassVal !== value) value = value + ' ' + ngClassVal;
-          element[0].className = trim(existing + value);
+          element.removeClass(isArray(oldVal) ? oldVal.join(' ') : oldVal)
+          element.addClass(isArray(newVal) ? newVal.join(' ') : newVal);
         }
       });
     };
@@ -571,11 +566,17 @@ function ngClass(selector) {
  * @name angular.directive.ng:class
  *
  * @description
- * The `ng:class` allows you to set CSS class on HTML element
- * conditionally.
+ * The `ng:class` allows you to set CSS class on HTML element dynamically by databinding an
+ * expression that represents all classes to be added.
+ *
+ * The directive won't add duplicate classes if a particular class was already set.
+ *
+ * When the expression changes, the previously added classes are removed and only then the classes
+ * new classes are added.
  *
  * @element ANY
- * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval.
+ * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
+ *   of the evaluation can be a string representing space delimited class names or an array.
  *
  * @example
    <doc:example>
@@ -612,12 +613,15 @@ angularDirective("ng:class", ngClass(function(){return true;}));
  *
  * @description
  * The `ng:class-odd` and `ng:class-even` works exactly as
- * `ng:class`, except it works in conjunction with `ng:repeat`
- * and takes affect only on odd (even) rows.
+ * {@link angular.directive.ng:class ng:class}, except it works in conjunction with `ng:repeat` and
+ * takes affect only on odd (even) rows.
+ *
+ * This directive can be applied only within a scope of an
+ * {@link angular.widget.@ng:repeat ng:repeat}.
  *
  * @element ANY
- * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. Must be
- *  inside `ng:repeat`.
+ * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
+ *   of the evaluation can be a string representing space delimited class names or an array.
  *
  * @example
    <doc:example>
@@ -650,12 +654,15 @@ angularDirective("ng:class-odd", ngClass(function(i){return i % 2 === 0;}));
  *
  * @description
  * The `ng:class-odd` and `ng:class-even` works exactly as
- * `ng:class`, except it works in conjunction with `ng:repeat`
- * and takes affect only on odd (even) rows.
+ * {@link angular.directive.ng:class ng:class}, except it works in conjunction with `ng:repeat` and
+ * takes affect only on odd (even) rows.
+ *
+ * This directive can be applied only within a scope of an
+ * {@link angular.widget.@ng:repeat ng:repeat}.
  *
  * @element ANY
- * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. Must be
- *  inside `ng:repeat`.
+ * @param {expression} expression {@link guide/dev_guide.expressions Expression} to eval. The result
+ *   of the evaluation can be a string representing space delimited class names or an array.
  *
  * @example
    <doc:example>
diff --git a/src/jqLite.js b/src/jqLite.js
index 8cef64da..122684a5 100644
--- a/src/jqLite.js
+++ b/src/jqLite.js
@@ -155,16 +155,24 @@ function JQLiteHasClass(element, selector, _) {
 }
 
 function JQLiteRemoveClass(element, selector) {
-  element.className = trim(
-      (" " + element.className + " ")
-      .replace(/[\n\t]/g, " ")
-      .replace(" " + selector + " ", " ")
-  );
+  if (selector) {
+    forEach(selector.split(' '), function(cssClass) {
+      element.className = trim(
+          (" " + element.className + " ")
+          .replace(/[\n\t]/g, " ")
+          .replace(" " + trim(cssClass) + " ", " ")
+      );
+    });
+  }
 }
 
 function JQLiteAddClass(element, selector) {
-  if (selector && !JQLiteHasClass(element, selector)) {
-    element.className = trim(element.className + ' ' + selector);
+  if (selector) {
+    forEach(selector.split(' '), function(cssClass) {
+      if (!JQLiteHasClass(element, cssClass)) {
+        element.className = trim(element.className + ' ' + trim(cssClass));
+      }
+    });
   }
 }
 
diff --git a/test/BinderSpec.js b/test/BinderSpec.js
index ecfe0682..68513f62 100644
--- a/test/BinderSpec.js
+++ b/test/BinderSpec.js
@@ -393,14 +393,6 @@ describe('Binder', function(){
     assertHidden(scope.$element);
   });
 
-  it('BindClassUndefined', function(){
-    var scope = this.compile('<div ng:class="undefined"/>');
-    scope.$apply();
-
-    assertEquals(
-        '<div class="undefined" ng:class="undefined"></div>',
-        sortedHtml(scope.$element));
-  });
 
   it('BindClass', function(){
     var scope = this.compile('<div ng:class="clazz"/>');
diff --git a/test/directivesSpec.js b/test/directivesSpec.js
index 1d26973c..314f9a88 100644
--- a/test/directivesSpec.js
+++ b/test/directivesSpec.js
@@ -196,13 +196,103 @@ describe("directive", function(){
       expect(element.hasClass('B')).toBe(false);
     });
 
-    it('should support adding multiple classes', function(){
+
+    it('should support adding multiple classes via an array', function(){
       var scope = compile('<div class="existing" ng:class="[\'A\', \'B\']"></div>');
       scope.$digest();
       expect(element.hasClass('existing')).toBeTruthy();
       expect(element.hasClass('A')).toBeTruthy();
       expect(element.hasClass('B')).toBeTruthy();
     });
+
+
+    it('should support adding multiple classes via a space delimited string', function(){
+      var scope = compile('<div class="existing" ng:class="\'A B\'"></div>');
+      scope.$digest();
+      expect(element.hasClass('existing')).toBeTruthy();
+      expect(element.hasClass('A')).toBeTruthy();
+      expect(element.hasClass('B')).toBeTruthy();
+    });
+
+
+    it('should preserve class added post compilation with pre-existing classes', function() {
+      var scope = compile('<div class="existing" ng:class="dynClass"></div>');
+      scope.dynClass = 'A';
+      scope.$digest();
+      expect(element.hasClass('existing')).toBe(true);
+
+      // add extra class, change model and eval
+      element.addClass('newClass');
+      scope.dynClass = 'B';
+      scope.$digest();
+
+      expect(element.hasClass('existing')).toBe(true);
+      expect(element.hasClass('B')).toBe(true);
+      expect(element.hasClass('newClass')).toBe(true);
+    });
+
+
+    it('should preserve class added post compilation without pre-existing classes"', function() {
+      var scope = compile('<div ng:class="dynClass"></div>');
+      scope.dynClass = 'A';
+      scope.$digest();
+      expect(element.hasClass('A')).toBe(true);
+
+      // add extra class, change model and eval
+      element.addClass('newClass');
+      scope.dynClass = 'B';
+      scope.$digest();
+
+      expect(element.hasClass('B')).toBe(true);
+      expect(element.hasClass('newClass')).toBe(true);
+    });
+
+
+    it('should preserve other classes with similar name"', function() {
+      var scope = compile('<div class="ui-panel ui-selected" ng:class="dynCls"></div>');
+      scope.dynCls = 'panel';
+      scope.$digest();
+      scope.dynCls = 'foo';
+      scope.$digest();
+      expect(element.attr('class')).toBe('ui-panel ui-selected ng-directive foo');
+    });
+
+
+    it('should not add duplicate classes', function() {
+      var scope = compile('<div class="panel bar" ng:class="dynCls"></div>');
+      scope.dynCls = 'panel';
+      scope.$digest();
+      expect(element.attr('class')).toBe('panel bar ng-directive');
+    });
+
+
+    it('should remove classes even if it was specified via class attribute', function() {
+      var scope = compile('<div class="panel bar" ng:class="dynCls"></div>');
+      scope.dynCls = 'panel';
+      scope.$digest();
+      scope.dynCls = 'window';
+      scope.$digest();
+      expect(element.attr('class')).toBe('bar ng-directive window');
+    });
+
+
+    it('should remove classes even if they were added by another code', function() {
+      var scope = compile('<div ng:class="dynCls"></div>');
+      scope.dynCls = 'foo';
+      scope.$digest();
+      element.addClass('foo');
+      scope.dynCls = '';
+      scope.$digest();
+      expect(element.attr('class')).toBe('ng-directive');
+    });
+
+
+    it('should convert undefined and null values to an empty string', function() {
+      var scope = compile('<div ng:class="dynCls"></div>');
+      scope.dynCls = [undefined, null];
+      scope.$digest();
+      expect(element.attr('class')).toBe('ng-directive');
+    });
   });
 
 
diff --git a/test/jqLiteSpec.js b/test/jqLiteSpec.js
index f2a99943..673bee78 100644
--- a/test/jqLiteSpec.js
+++ b/test/jqLiteSpec.js
@@ -190,14 +190,15 @@ describe('jqLite', function(){
     });
 
 
-    describe('addClass', function(){
-      it('should allow adding of class', function(){
+    describe('addClass', function() {
+      it('should allow adding of class', function() {
         var selector = jqLite([a, b]);
         expect(selector.addClass('abc')).toEqual(selector);
         expect(jqLite(a).hasClass('abc')).toEqual(true);
         expect(jqLite(b).hasClass('abc')).toEqual(true);
       });
 
+
       it('should ignore falsy values', function() {
         var jqA = jqLite(a);
         expect(jqA[0].className).toBe('');
@@ -211,6 +212,28 @@ describe('jqLite', function(){
         jqA.addClass(false);
         expect(jqA[0].className).toBe('');
       });
+
+
+      it('should allow multiple classes to be added in a single string', function() {
+        var jqA = jqLite(a);
+        expect(a.className).toBe('');
+
+        jqA.addClass('foo bar baz');
+        expect(a.className).toBe('foo bar baz');
+      });
+
+
+      it('should not add duplicate classes', function() {
+        var jqA = jqLite(a);
+        expect(a.className).toBe('');
+
+        a.className = 'foo';
+        jqA.addClass('foo');
+        expect(a.className).toBe('foo');
+
+        jqA.addClass('bar foo baz');
+        expect(a.className).toBe('foo bar baz');
+      });
     });
 
 
@@ -246,6 +269,7 @@ describe('jqLite', function(){
         expect(jqLite(b).hasClass('abc')).toEqual(false);
       });
 
+
       it('should correctly remove middle class', function() {
         var element = jqLite('<div class="foo bar baz"></div>');
         expect(element.hasClass('bar')).toBe(true);
@@ -256,6 +280,15 @@ describe('jqLite', function(){
         expect(element.hasClass('bar')).toBe(false);
         expect(element.hasClass('baz')).toBe(true);
       });
+
+
+      it('should remove multiple classes specified as one string', function() {
+        var jqA = jqLite(a);
+
+        a.className = 'foo bar baz';
+        jqA.removeClass('foo baz noexistent');
+        expect(a.className).toBe('bar');
+      });
     });
   });