feat(reactivity): add isShallow api

packages/reactivity/__tests__/ref.spec.ts

@@ -10,6 +10,7 @@ import {
 } from '../src/index'
 import { computed } from '@vue/runtime-dom'
 import { shallowRef, unref, customRef, triggerRef } from '../src/ref'
+import { isShallow } from '../src/reactive'
 
 describe('reactivity/ref', () => {
   it('should hold a value', () => {
@@ -227,6 +228,10 @@ describe('reactivity/ref', () => {
     expect(dummy).toBe(2)
   })
 
+  test('shallowRef isShallow', () => {
+    expect(isShallow(shallowRef({ a: 1 }))).toBe(true)
+  })
+
   test('isRef', () => {
     expect(isRef(ref(1))).toBe(true)
     expect(isRef(computed(() => 1))).toBe(true)

packages/reactivity/__tests__/shallowReactive.spec.ts

@@ -1,4 +1,10 @@
-import { isReactive, reactive, shallowReactive } from '../src/reactive'
+import {
+  isReactive,
+  isShallow,
+  reactive,
+  shallowReactive,
+  shallowReadonly
+} from '../src/reactive'
 
 import { effect } from '../src/effect'
 
@@ -24,6 +30,11 @@ describe('shallowReactive', () => {
     expect(isReactive(reactiveProxy.foo)).toBe(true)
   })
 
+  test('isShallow', () => {
+    expect(isShallow(shallowReactive({}))).toBe(true)
+    expect(isShallow(shallowReadonly({}))).toBe(true)
+  })
+
   describe('collections', () => {
     test('should be reactive', () => {
       const shallowSet = shallowReactive(new Set())