fix(radioButton): arrowkey navigation with disabled buttons

Closes #1040.

src/components/radioButton/radioButton.js

@@ -141,10 +141,16 @@ function mdRadioGroupDirective($mdUtil, $mdConstant, $mdTheming) {
     );
 
     if (buttons.count()) {
+      var validate = function (button) {
+        // If disabled, then NOT valid
+        return !angular.element(button).attr("disabled");
+      };
       var selected = parent[0].querySelector('md-radio-button.md-checked');
-      var target = buttons[increment < 0 ? 'previous' : 'next'](selected) || buttons.first();
+      var target = buttons[increment < 0 ? 'previous' : 'next'](selected, validate) || buttons.first();
       // Activate radioButton's click listener (triggerHandler won't create a real click event)
       angular.element(target).triggerHandler('click');
+
+
     }
   }
 

src/components/radioButton/radioButton.spec.js

@@ -156,6 +156,40 @@ describe('radioButton', function() {
       expect($rootScope.color).toBe('white');
     }));
 
+    it('should skip disabled on arrow key', inject(function($compile, $rootScope, $mdConstant) {
+      var element = $compile(
+        '<md-radio-group ng-model="color">' +
+        '  <md-radio-button value="red"   ></md-radio-button>' +
+        '  <md-radio-button value="white" ng-disabled="isDisabled"></md-radio-button>' +
+        '  <md-radio-button value="blue" ></md-radio-button>' +
+        '</md-radio-group>'
+      )($rootScope);
+      var rbGroupElement = element.eq(0);
+
+      $rootScope.$apply('isDisabled = true');
+      $rootScope.$apply('color = "red"');
+      expect($rootScope.color).toBe("red");
+
+
+      rightArrow();   expect($rootScope.color).toEqual('blue');
+      rightArrow();   expect($rootScope.color).toEqual('red');
+      rightArrow();   expect($rootScope.color).toEqual('blue');
+
+
+      $rootScope.$apply('isDisabled = false');
+
+      rightArrow();
+      rightArrow();   expect($rootScope.color).toEqual('white');
+      rightArrow();   expect($rootScope.color).toEqual('blue');
+
+      function rightArrow() {
+          rbGroupElement.triggerHandler({
+            type: 'keydown',
+            keyCode: $mdConstant.KEY_CODE.RIGHT_ARROW
+          });
+        }
+    }));
+
 
     it('should allow {{expr}} as value', inject(function($compile, $rootScope) {
       $rootScope.some = 11;

src/core/util/iterator.spec.js

@@ -254,6 +254,32 @@ describe('iterator', function() {
 
     });
 
+  });
+
+  describe('use to provide navigation with validation ', function () {
+    var list, iter;
+    var validate = function(item) { return (item !== 14) && (item !== 'Andrew'); };
+
+    beforeEach(inject(function ($mdUtil) {
+      list = [ 13, 14, 'Marcy', 15, 'Andrew', 16, 21, 'Adam', 37, 'Max', 99 ];
+      iter = $mdUtil.iterator(list);
+    }));
+
+    it('should use next() properly', function () {
+
+      expect( iter.next(13,      validate) ).toBe('Marcy');
+      expect( iter.next('Marcy', validate) ).toBe(15);
+      expect( iter.next(15,      validate) ).toBe(16);
+
+    });
+
+    it('should use previous() properly', function () {
+
+      expect( iter.previous(16,      validate) ).toBe(15);
+      expect( iter.previous(15,      validate) ).toBe('Marcy');
+      expect( iter.previous('Marcy', validate) ).toBe(13);
+
+    });
 
   });
 

src/core/util/util.js

@@ -329,14 +329,17 @@ angular.module('material.core')
      * @param {optional} validate
      * @returns {*}
      */
-    function next(item, validate) {
+    function next(item, validate, limit) {
       validate = validate || trueFn;
 
       if (contains(item)) {
         var index = indexOf(item) + 1,
-        found = inRange(index) ? _items[ index ] : (reloop ? first() : null);
+            found = inRange(index) ? _items[ index ] : (reloop ? first() : null);
 
-        return validate(found) ? found : next(found, validate);
+        // Infinite loop check...
+        if ( reloop && (indexOf(found) === limit) ) return null;
+
+        return validate(found) ? found : next(found, validate, limit || index);
       }
 
       return null;