fix(ngChecked): ensure that ngChecked doesn't interfere with ngModel

Corrects an issue which occurs when an element's ng-modeol and ng-checked attributes have the same
value.

Closes #10662
Closes #10664

Author: LeonardoBraga

src/ng/directive/attrs.js

@@ -341,22 +341,34 @@
 
 var ngAttributeAliasDirectives = {};
 
-
 // boolean attrs are evaluated
 forEach(BOOLEAN_ATTR, function(propName, attrName) {
   // binding to multiple is not supported
   if (propName == "multiple") return;
 
+  function defaultLinkFn(scope, element, attr) {
+    scope.$watch(attr[normalized], function ngBooleanAttrWatchAction(value) {
+      attr.$set(attrName, !!value);
+    });
+  }
+
   var normalized = directiveNormalize('ng-' + attrName);
+  var linkFn = defaultLinkFn;
+
+  if (propName === 'checked') {
+    linkFn = function(scope, element, attr) {
+      // ensuring ngChecked doesn't interfere with ngModel when both are set on the same input
+      if (attr.ngModel !== attr[normalized]) {
+        defaultLinkFn(scope, element, attr);
+      }
+    };
+  }
+
   ngAttributeAliasDirectives[normalized] = function() {
     return {
       restrict: 'A',
       priority: 100,
-      link: function(scope, element, attr) {
-        scope.$watch(attr[normalized], function ngBooleanAttrWatchAction(value) {
-          attr.$set(attrName, !!value);
-        });
-      }
+      link: linkFn
     };
   };
 });

test/ng/directive/booleanAttrsSpec.js

@@ -42,6 +42,22 @@ describe('boolean attr directives', function() {
   }));
 
 
+  it('should not bind checked when ngModel is present', inject(function($rootScope, $compile) {
+    // test for https://github.com/angular/angular.js/issues/10662
+    element = $compile('<input type="checkbox" ng-model="value" ng-false-value="\'false\'" ' +
+      'ng-true-value="\'true\'" ng-checked="value" />')($rootScope);
+    $rootScope.value = 'true';
+    $rootScope.$digest();
+    expect(element[0].checked).toBe(true);
+    browserTrigger(element, 'click');
+    expect(element[0].checked).toBe(false);
+    expect($rootScope.value).toBe('false');
+    browserTrigger(element, 'click');
+    expect(element[0].checked).toBe(true);
+    expect($rootScope.value).toBe('true');
+  }));
+
+
   it('should bind selected', inject(function($rootScope, $compile) {
     element = $compile('<select><option value=""></option><option ng-selected="isSelected">Greetings!</option></select>')($rootScope);
     jqLite(document.body).append(element);