test(ngOptions): fix flaky test on Firefox 54+

Author: gkalpak

test/ng/directive/ngOptionsSpec.js

@@ -2923,6 +2923,9 @@ describe('ngOptions', function() {
 
 
     it('should not re-set the `selected` property if it already has the correct value', function() {
+      var optionProto;
+      var originalSelectedDescriptor;
+
       scope.values = [{name: 'A'}, {name: 'B'}];
       createMultiSelect();
 
@@ -2932,14 +2935,51 @@ describe('ngOptions', function() {
 
       // Set up spies
       forEach(options, function(option, i) {
-        optionsSetSelected[i] = jasmine.createSpy('optionSetSelected' + i);
-        _selected[i] = option.selected;
-        Object.defineProperty(option, 'selected', {
-          get: function() { return _selected[i]; },
-          set: optionsSetSelected[i].and.callFake(function(value) { _selected[i] = value; })
-        });
+        var setSelected = function(value) { _selected[i] = value; };
+        optionsSetSelected[i] = jasmine.createSpy('optionSetSelected' + i).and.callFake(setSelected);
+        setSelected(option.selected);
       });
 
+      if (!isFunction(Object.getOwnPropertyDescriptor)) {
+        forEach(options, function(option, i) {
+          Object.defineProperty(option, 'selected', {
+            get: function() { return _selected[i]; },
+            set: optionsSetSelected[i]
+          });
+        });
+      } else {
+        // Support: Firefox 54+
+        // We cannot use the above (simpler) method for all browsers, because of Firefox 54+, which
+        // is very flaky when the getter/setter property is defined on the element itself and not
+        // the prototype. (Possibly the result of some (buggy?) optimization.)
+        optionProto = Object.getPrototypeOf(options[0]);
+        originalSelectedDescriptor = Object.getOwnPropertyDescriptor(optionProto, 'selected');
+
+        var getSelected = function(index) { return _selected[index]; };
+        var setSelected = function(index, value) { optionsSetSelected[index](value); };
+        var getSelectedOriginal = function(option) {
+          return originalSelectedDescriptor.get.call(option);
+        };
+        var setSelectedOriginal = function(option, value) {
+          originalSelectedDescriptor.set.call(option, value);
+        };
+        var getIndexAndCall = function(option, foundFn, notFoundFn, value) {
+          for (var i = 0, ii = options.length; i < ii; ++i) {
+            if (options[i] === option) return foundFn(i, value);
+          }
+          return notFoundFn(option, value);
+        };
+
+        Object.defineProperty(optionProto, 'selected', {
+          get: function() {
+            return getIndexAndCall(this, getSelected, getSelectedOriginal);
+          },
+          set: function(value) {
+            return getIndexAndCall(this, setSelected, setSelectedOriginal, value);
+          }
+        });
+      }
+
       // Select `optionA`
       scope.$apply('selected = [values[0]]');
 
@@ -2999,6 +3039,11 @@ describe('ngOptions', function() {
       expect(options[1].selected).toBe(false);
       optionsSetSelected[0].calls.reset();
       optionsSetSelected[1].calls.reset();
+
+      // Restore `originalSelectedDescriptor`
+      if (originalSelectedDescriptor) {
+        Object.defineProperty(optionProto, 'selected', originalSelectedDescriptor);
+      }
     });
 
     if (window.MutationObserver) {