fix(api-watch): watching nested ref array w/ deep doesn't work (#808)

Co-authored-by: webfansplz <>

src/apis/watch.ts

@@ -341,7 +341,11 @@ function createWatcher(
   }
 
   const applyCb = (n: any, o: any) => {
-    if (isMultiSource && n.every((v: any, i: number) => Object.is(v, o[i])))
+    if (
+      !deep &&
+      isMultiSource &&
+      n.every((v: any, i: number) => Object.is(v, o[i]))
+    )
       return
     // cleanup before running cb again
     runCleanup()

test/v3/runtime-core/apiWatch.spec.ts

@@ -572,4 +572,14 @@ describe('api: watch', () => {
     await nextTick()
     expect(dummy).toEqual([1, 2])
   })
+
+  // #805 #807
+  it('watching sources: [ref<[]>] w/ deep', async () => {
+    const foo = ref([1])
+    const cb = jest.fn()
+    watch([foo], cb, { deep: true })
+    foo.value.push(2)
+    await nextTick()
+    expect(cb).toBeCalledTimes(1)
+  })
 })