chore(watchEffect): migrating watchEffect warn and test cases from vue3. (#757)

Author: ygj6

src/apis/watch.ts

@@ -103,8 +103,6 @@ function getWatcherOption(options?: Partial<WatchOptions>): WatchOptions {
 function getWatchEffectOption(options?: Partial<WatchOptions>): WatchOptions {
   return {
     ...{
-      immediate: true,
-      deep: false,
       flush: 'pre',
     },
     ...options,
@@ -208,6 +206,21 @@ function createWatcher(
   cb: WatchCallback<any> | null,
   options: WatchOptions
 ): () => void {
+  if (__DEV__ && !cb) {
+    if (options.immediate !== undefined) {
+      warn(
+        `watch() "immediate" option is only respected when using the ` +
+          `watch(source, callback, options?) signature.`
+      )
+    }
+    if (options.deep !== undefined) {
+      warn(
+        `watch() "deep" option is only respected when using the ` +
+          `watch(source, callback, options?) signature.`
+      )
+    }
+  }
+
   const flushMode = options.flush
   const isSync = flushMode === 'sync'
   let cleanup: (() => void) | null

test/apis/watch.spec.js

@@ -446,6 +446,40 @@ describe('api/watch', () => {
       vm.count++
       expect(spy).toHaveBeenLastCalledWith(1)
     })
+
+    it('warn immediate option when using effect', async () => {
+      const count = ref(0)
+      let dummy
+      watchEffect(
+        () => {
+          dummy = count.value
+        },
+        { immediate: false }
+      )
+      expect(dummy).toBe(0)
+      expect(`"immediate" option is only respected`).toHaveBeenWarned()
+
+      count.value++
+      await nextTick()
+      expect(dummy).toBe(1)
+    })
+
+    it('warn and not respect deep option when using effect', async () => {
+      const arr = ref([1, [2]])
+      const spy = jest.fn()
+      watchEffect(
+        () => {
+          spy()
+          return arr
+        },
+        { deep: true }
+      )
+      expect(spy).toHaveBeenCalledTimes(1)
+      arr.value[1][0] = 3
+      await nextTick()
+      expect(spy).toHaveBeenCalledTimes(1),
+        expect(`"deep" option is only respected`).toHaveBeenWarned()
+    })
   })
 
   describe('Multiple sources', () => {