fix(watch): always triggers when watching multiple refs

src/apis/watch.ts

@@ -295,6 +295,7 @@ function createWatcher(
   }
 
   let deep = options.deep
+  let isMultiSource = false
 
   let getter: () => any
   if (isRef(source)) {
@@ -303,6 +304,7 @@ function createWatcher(
     getter = () => source
     deep = true
   } else if (isArray(source)) {
+    isMultiSource = true
     getter = () =>
       source.map((s) => {
         if (isRef(s)) {
@@ -339,6 +341,8 @@ function createWatcher(
   }
 
   const applyCb = (n: any, o: any) => {
+    if (isMultiSource && n.every((v: any, i: number) => Object.is(v, o[i])))
+      return
     // cleanup before running cb again
     runCleanup()
     return cb(n, o, registerCleanup)

test/apis/watch.spec.js

@@ -5,6 +5,7 @@ const {
   watch,
   watchEffect,
   set,
+  computed,
   nextTick,
 } = require('../../src')
 const { mockWarn } = require('../helpers')
@@ -821,4 +822,28 @@ describe('api/watch', () => {
 
     expect(cb).toHaveBeenCalled()
   })
+
+  it('watching sources: ref<[]>', async () => {
+    const foo = ref([1])
+    const cb = jest.fn()
+    watch(foo, cb)
+    foo.value = foo.value.slice()
+    await nextTick()
+    expect(cb).toBeCalledTimes(1)
+  })
+
+  it('watching multiple sources: computed', async () => {
+    const number = ref(1)
+    const div2 = computed(() => {
+      return number.value > 2 ? '>2' : '<=2'
+    })
+    const div3 = computed(() => {
+      return number.value > 3 ? '>3' : '<=3'
+    })
+    const cb = jest.fn()
+    watch([div2, div3], cb)
+    number.value = 2
+    await nextTick()
+    expect(cb).toHaveBeenCalledTimes(0)
+  })
 })