feat(accordion): support spacebar to toggle group

- Allow spacebar to toggle the accordion group

Closes #4319
Resolves #4249

src/accordion/accordion.js

@@ -88,9 +88,11 @@ angular.module('ui.bootstrap.accordion', ['ui.bootstrap.collapse'])
         }
       });
 
-      scope.toggleOpen = function() {
+      scope.toggleOpen = function($event) {
         if (!scope.isDisabled) {
-          scope.isOpen = !scope.isOpen;
+          if (!$event || $event.which === 32) {
+            scope.isOpen = !scope.isOpen;
+          }
         }
       };
     }

src/accordion/test/accordion.spec.js

@@ -222,6 +222,22 @@ describe('accordion', function() {
         scope.$digest();
         expect(group).not.toHaveClass('panel-open');
       });
+
+      it('should toggle element on spacebar when focused', function() {
+        var group = groups.eq(0);
+        findGroupLink(0)[0].focus();
+        var e = $.Event('keypress');
+        e.which = 32;
+        findGroupLink(0).trigger(e);
+
+        expect(group).toHaveClass('panel-open');
+
+        e = $.Event('keypress');
+        e.which = 32;
+        findGroupLink(0).trigger(e);
+
+        expect(group).not.toHaveClass('panel-open');
+      });
     });
 
     describe('with open-class attribute', function() {

template/accordion/accordion-group.html

@@ -1,5 +1,5 @@
 <div class="panel {{panelClass || 'panel-default'}}">
-  <div class="panel-heading">
+  <div class="panel-heading" ng-keypress="toggleOpen($event)">
     <h4 class="panel-title">
       <a href tabindex="0" class="accordion-toggle" ng-click="toggleOpen()" accordion-transclude="heading"><span ng-class="{'text-muted': isDisabled}">{{heading}}</span></a>
     </h4>