feat(mdAria): Checks child nodes for aria-label

Closes #567

src/core/services/aria/aria.js

@@ -13,14 +13,28 @@ function AriaService($$rAF, $log) {
   };
 
   /**
-   * Check if expected attribute has been specified on the target element
+   * Check if expected attribute has been specified on the target element or child
    * @param element
    * @param attrName
    * @param {optional} defaultValue What to set the attr to if no value is found
    */
   function expect(element, attrName, defaultValue) {
-    var node = element[0];
-    if (!node.hasAttribute(attrName)) {
+    var node = element[0],
+        hasChildren = node.hasChildNodes(),
+        childHasAttribute = false;
+
+    if(hasChildren) {
+      var children = node.childNodes;
+      for(var i=0; i<children.length; i++){
+        var child = children[i];
+        if(child.nodeType === 1 && child.hasAttribute(attrName)) {
+          if(!isHidden(child)){
+            childHasAttribute = true;
+          }
+        }
+      }
+    }
+    if (!node.hasAttribute(attrName) && !childHasAttribute) {
 
       defaultValue = angular.isString(defaultValue) && defaultValue.trim() || '';
       if (defaultValue.length) {
@@ -47,5 +61,10 @@ function AriaService($$rAF, $log) {
     });
   }
 
+  function isHidden(el) {
+    var style = el.currentStyle ? el.currentStyle :
+                          getComputedStyle(el, null);
+    return (style.display === 'none');
+  }
 }
 })();

src/core/services/aria/aria.spec.js

@@ -0,0 +1,33 @@
+describe('$mdAria service', function() {
+  beforeEach(module('material.core'));
+
+  describe('expecting attributes', function(){
+    it('should warn if element is missing text', inject(function($compile, $rootScope, $log, $mdAria) {
+      spyOn($log, 'warn');
+      var button = $compile('<button><md-icon></md-icon></button>')($rootScope);
+
+      $mdAria.expect(button, 'aria-label');
+
+      expect($log.warn).toHaveBeenCalled();
+    }));
+
+    it('should not warn if child element has attribute', inject(function($compile, $rootScope, $log, $mdAria) {
+      spyOn($log, 'warn');
+      var button = $compile('<button><md-icon aria-label="text"></md-icon></button>')($rootScope);
+
+      $mdAria.expect(button, 'aria-label');
+
+      expect($log.warn).not.toHaveBeenCalled();
+    }));
+
+    xit('should warn if child with attribute is hidden', inject(function($compile, $rootScope, $log, $mdAria) {
+      spyOn($log, 'warn');
+      var button = $compile('<button><md-icon aria-label="text" style="display: none;"></md-icon></button>')($rootScope);
+
+      $mdAria.expect(button, 'aria-label');
+
+      expect($log.warn).toHaveBeenCalled();
+    }));
+  });
+
+});