fix(getCurrentInstance): emit event (#624)

Author: pikax

src/runtimeContext.ts

@@ -145,7 +145,7 @@ export declare interface ComponentInternalInstance {
   isDeactivated: boolean
 }
 
-export function getCurrentVu2Instance() {
+export function getCurrentVue2Instance() {
   return currentInstance
 }
 
@@ -173,6 +173,9 @@ function toVue3ComponentInstance(
     update: vue2Instance.$forceUpdate,
     uid: vue2Instance._uid,
 
+    // $emit is defined on prototype and it expected to be bound
+    emit: vue2Instance.$emit.bind(vue2Instance),
+
     parent: null,
     root: null as any,
   } as unknown) as ComponentInternalInstance
@@ -183,7 +186,6 @@ function toVue3ComponentInstance(
     'props',
     'attrs',
     'refs',
-    'emit',
     'vnode',
     'slots',
   ] as const

src/utils/instance.ts

@@ -1,6 +1,6 @@
 import { ComponentInstance } from '../component'
 import vmStateManager from './vmStateManager'
-import { setCurrentInstance, getCurrentVu2Instance } from '../runtimeContext'
+import { setCurrentInstance, getCurrentVue2Instance } from '../runtimeContext'
 import { Ref, isRef } from '../apis'
 import { hasOwn, proxy, warn } from './utils'
 import { createSlotProxy, resolveSlots } from './helper'
@@ -112,7 +112,7 @@ export function activateCurrentInstance(
   fn: (vm_: ComponentInstance) => any,
   onError?: (err: Error) => void
 ) {
-  let preVm = getCurrentVu2Instance()
+  let preVm = getCurrentVue2Instance()
   setCurrentInstance(vm)
   try {
     return fn(vm)

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

@@ -45,7 +45,12 @@ describe('component: proxy', () => {
       components: {
         Comp,
       },
-      template: '<Comp/>',
+      data() {
+        return {
+          update: 0,
+        }
+      },
+      template: '<Comp @update="update++"/>',
     }
     const app = createApp(Parent).mount(document.createElement('div'))
 
@@ -60,10 +65,17 @@ describe('component: proxy', () => {
       instance!.parent && instance!.parent.proxy
     )
     expect(instanceProxy.$root).toBe(instance!.root.proxy)
-    expect(instanceProxy.$emit).toBe(instance!.emit)
     expect(instance.isMounted).toBe(true)
     expect(instance.isUnmounted).toBe(false)
 
+    // @ts-expect-error no typings
+    expect(app.update).toBe(0)
+
+    instance!.emit('update')
+
+    // @ts-expect-error no typings
+    expect(app.update).toBe(1)
+
     // expect(instanceProxy.$el).toBe(instance!.vnode.el)
     // expect(instanceProxy.$options).toBe(instance!.type)