chore: Add async test with immediate watcher

Author: xanf

Diff for: test/resources/components/component-with-watch-immediate.vue

@@ -0,0 +1,22 @@
+<script>
+export default {
+  props: ['prop1'],
+  data: function() {
+    return {
+      data1: null
+    }
+  },
+
+  watch: {
+    prop1: {
+      handler() {
+        this.data1 = this.prop1
+      },
+      immediate: true
+    }
+  }
+}
+</script>
+<template>
+  <h1>test</h1>
+</template>

Diff for: test/specs/config.spec.js

@@ -104,9 +104,7 @@ describeWithShallowAndMount('config', mountingMethod => {
       localVue
     })
     expect(wrapper.vm.prop1).to.equal('example')
-    wrapper.setProps({
-      prop1: 'new value'
-    })
+    wrapper.vm.prop1 = 'new value'
     expect(console.error).calledWith(sandbox.match('[Vue warn]'))
   })
 })

Diff for: test/specs/wrapper/setProps.spec.js

@@ -1,6 +1,7 @@
 import { compileToFunctions } from 'vue-template-compiler'
 import ComponentWithProps from '~resources/components/component-with-props.vue'
 import ComponentWithWatch from '~resources/components/component-with-watch.vue'
+import ComponentWithWatchImmediate from '~resources/components/component-with-watch-immediate.vue'
 import { describeWithShallowAndMount, vueVersion } from '~resources/utils'
 import { itDoNotRunIf } from 'conditional-specs'
 import Vue from 'vue'
@@ -244,6 +245,17 @@ describeWithShallowAndMount('setProps', mountingMethod => {
     expect(wrapper.vm.propA).to.equal('value')
   })
 
+  it('correctly sets props in async mode when component has immediate watchers', async () => {
+    const wrapper = mountingMethod(ComponentWithWatchImmediate, {
+      sync: false
+    })
+
+    const prop1 = 'testest'
+    wrapper.setProps({ prop1 })
+    await Vue.nextTick()
+    expect(wrapper.vm.prop1).to.equal(prop1)
+  })
+
   it('throws an error if node is not a Vue instance', () => {
     const message = 'wrapper.setProps() can only be called on a Vue instance'
     const compiled = compileToFunctions('<div><p></p></div>')