From 6fcfdbd83f424eba19933d453420d762c9bad767 Mon Sep 17 00:00:00 2001
From: Kenneth Crawford <kmc059000@users.noreply.github.com>
Date: Sun, 26 Mar 2017 21:41:29 -0500
Subject: [PATCH] warn and handle missing get in computed (fix #5265) (#5267)

---
 src/core/instance/state.js                  | 11 ++++++++-
 test/unit/features/options/computed.spec.js | 27 +++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/core/instance/state.js b/src/core/instance/state.js
index 1a8d66a5b67..74977f852d3 100644
--- a/src/core/instance/state.js
+++ b/src/core/instance/state.js
@@ -147,7 +147,16 @@ function initComputed (vm: Component, computed: Object) {
 
   for (const key in computed) {
     const userDef = computed[key]
-    const getter = typeof userDef === 'function' ? userDef : userDef.get
+    let getter = typeof userDef === 'function' ? userDef : userDef.get
+    if (process.env.NODE_ENV !== 'production') {
+      if (getter === undefined) {
+        warn(
+          `No getter function has been defined for computed property "${key}".`,
+          vm
+        )
+        getter = noop
+      }
+    }
     // create internal watcher for the computed property.
     watchers[key] = new Watcher(vm, getter, noop, computedWatcherOptions)
 
diff --git a/test/unit/features/options/computed.spec.js b/test/unit/features/options/computed.spec.js
index baed4a05418..9997c0b9251 100644
--- a/test/unit/features/options/computed.spec.js
+++ b/test/unit/features/options/computed.spec.js
@@ -48,6 +48,33 @@ describe('Options computed', () => {
     }).then(done)
   })
 
+  it('warn with setter and no getter', () => {
+    const vm = new Vue({
+      template: `
+        <div>
+          <test></test>
+        </div>
+      `,
+      components: {
+        test: {
+          data () {
+            return {
+              a: 1
+            }
+          },
+          computed: {
+            b: {
+              set (v) { this.a = v }
+            }
+          },
+          template: `<div>{{a}}</div>`
+        }
+      }
+    }).$mount()
+    expect(vm.$el.innerHTML).toBe('<div>1</div>')
+    expect('No getter function has been defined for computed property "b".').toHaveBeenWarned()
+  })
+
   it('watching computed', done => {
     const spy = jasmine.createSpy('watch computed')
     const vm = new Vue({