From d69d3bf76540c83cf3a1d39ecf45efc3f82510a8 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Fri, 18 Oct 2019 15:31:28 -0400
Subject: [PATCH] fix(reactivity): revert to Reflect.get and add test cases

---
 packages/reactivity/__tests__/effect.spec.ts | 30 ++++++++++++++++++++
 packages/reactivity/src/baseHandlers.ts      |  5 ++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/packages/reactivity/__tests__/effect.spec.ts b/packages/reactivity/__tests__/effect.spec.ts
index 340bf1093..32a7fbdfe 100644
--- a/packages/reactivity/__tests__/effect.spec.ts
+++ b/packages/reactivity/__tests__/effect.spec.ts
@@ -249,6 +249,36 @@ describe('reactivity/effect', () => {
     expect(dummy).toBe(newFunc)
   })
 
+  it('should observe chained getters relying on this', () => {
+    const obj = reactive({
+      a: 1,
+      get b() {
+        return this.a
+      }
+    })
+
+    let dummy
+    effect(() => (dummy = obj.b))
+    expect(dummy).toBe(1)
+    obj.a++
+    expect(dummy).toBe(2)
+  })
+
+  it('should observe methods relying on this', () => {
+    const obj = reactive({
+      a: 1,
+      b() {
+        return this.a
+      }
+    })
+
+    let dummy
+    effect(() => (dummy = obj.b()))
+    expect(dummy).toBe(1)
+    obj.a++
+    expect(dummy).toBe(2)
+  })
+
   it('should not observe set operations without a value change', () => {
     let hasDummy, getDummy
     const obj = reactive({ prop: 'value' })
diff --git a/packages/reactivity/src/baseHandlers.ts b/packages/reactivity/src/baseHandlers.ts
index 4ebdb0a33..0043af73f 100644
--- a/packages/reactivity/src/baseHandlers.ts
+++ b/packages/reactivity/src/baseHandlers.ts
@@ -12,9 +12,8 @@ const builtInSymbols = new Set(
 )
 
 function createGetter(isReadonly: boolean) {
-  return function get(target: any, key: string | symbol) {
-    // not using Reflect.get here for perf reasons
-    const res = target[key]
+  return function get(target: any, key: string | symbol, receiver: any) {
+    const res = Reflect.get(target, key, receiver)
     if (isSymbol(key) && builtInSymbols.has(key)) {
       return res
     }