test: fix Object.prototype.watch related warnings

src/core/instance/state.js

@@ -20,6 +20,7 @@ import {
   hasOwn,
   isReserved,
   handleError,
+  nativeWatch,
   validateProp,
   isPlainObject,
   isReservedAttribute
@@ -53,7 +54,9 @@ export function initState (vm: Component) {
     observe(vm._data = {}, true /* asRootData */)
   }
   if (opts.computed) initComputed(vm, opts.computed)
-  if (opts.watch) initWatch(vm, opts.watch)
+  if (opts.watch && opts.watch !== nativeWatch) {
+    initWatch(vm, opts.watch)
+  }
 }
 
 function checkOptionType (vm: Component, name: string) {

src/core/util/env.js

@@ -17,6 +17,9 @@ export const isAndroid = UA && UA.indexOf('android') > 0
 export const isIOS = UA && /iphone|ipad|ipod|ios/.test(UA)
 export const isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge
 
+// Firefix has a "watch" function on Object.prototype...
+export const nativeWatch = ({}).watch
+
 export let supportsPassive = false
 if (inBrowser) {
   try {

src/core/util/options.js

@@ -2,6 +2,7 @@
 
 import config from '../config'
 import { warn } from './debug'
+import { nativeWatch } from './env'
 import { set } from '../observer/index'
 
 import {
@@ -172,6 +173,9 @@ ASSET_TYPES.forEach(function (type) {
  * another, so we merge them as arrays.
  */
 strats.watch = function (parentVal: ?Object, childVal: ?Object): ?Object {
+  // work around Firefox's Object.prototype.watch...
+  if (parentVal === nativeWatch) parentVal = undefined
+  if (childVal === nativeWatch) childVal = undefined
   /* istanbul ignore if */
   if (!childVal) return Object.create(parentVal || null)
   if (!parentVal) return childVal

test/helpers/test-object-option.js

@@ -1,14 +1,14 @@
 import Vue from 'vue'
 
 export default function testObjectOption (name) {
-  it('should warn non object', () => {
+  it('should warn non object value', () => {
     const options = {}
     options[name] = () => {}
     new Vue(options)
     expect(`component option "${name}" should be an object`).toHaveBeenWarned()
   })
 
-  it('don\'t warn when is an object', () => {
+  it('should not warn valid object value', () => {
     const options = {}
     options[name] = {}
     new Vue(options)

test/unit/features/options/watch.spec.js

@@ -7,6 +7,8 @@ describe('Options watch', () => {
     spy = jasmine.createSpy('watch')
   })
 
+  testObjectOption('watch')
+
   it('basic usage', done => {
     const vm = new Vue({
       data: {
@@ -24,8 +26,6 @@ describe('Options watch', () => {
     }).then(done)
   })
 
-  testObjectOption('watch')
-
   it('string method name', done => {
     const vm = new Vue({
       data: {