fix: remove throw from errorHandler (#655)

Author: eddyerburgh

Diff for: packages/test-utils/src/mount.js

@@ -16,11 +16,16 @@ import { addScopedSlots } from './add-scoped-slots'
 
 Vue.config.productionTip = false
 Vue.config.devtools = false
-Vue.config.errorHandler = errorHandler
 
 export default function mount (component: Component, options: Options = {}): VueWrapper {
+  const existingErrorHandler = Vue.config.errorHandler
+  Vue.config.errorHandler = errorHandler
+
   warnIfNoWindow()
 
+  // Remove cached constructor
+  delete component._Ctor
+
   const vueConstructor = options.localVue || createLocalVue()
 
   const elm = options.attachToDocument
@@ -57,6 +62,8 @@ export default function mount (component: Component, options: Options = {}): Vue
     throw (componentsWithError[0]._error)
   }
 
+  Vue.config.errorHandler = existingErrorHandler
+
   const wrapperOptions = {
     attachedToDocument: !!mergedOptions.attachToDocument,
     sync: mergedOptions.sync

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

@@ -227,6 +227,40 @@ describeRunIf(process.env.TEST_ENV !== 'node',
       expect(fn).to.throw('Error in mounted')
     })
 
+    itDoNotRunIf(
+      vueVersion < 2.2,
+      'logs errors once after mount', (done) => {
+        Vue.config.errorHandler = null
+        const TestComponent = {
+          template: '<div/>',
+          updated: function () {
+            throw new Error('Error in updated')
+          }
+        }
+
+        const wrapper = mount(TestComponent, {
+          sync: false
+        })
+        wrapper.vm.$forceUpdate()
+        setTimeout(() => {
+          vueVersion > 2.1
+            ? expect(console.error).calledTwice
+            : expect(console.error).calledOnce
+          done()
+        })
+      })
+
+    it('restores user error handler after mount', () => {
+      const existingErrorHandler = () => {}
+      Vue.config.errorHandler = existingErrorHandler
+      const TestComponent = {
+        template: '<div/>'
+      }
+      mount(TestComponent)
+      expect(Vue.config.errorHandler).to.equal(existingErrorHandler)
+      Vue.config.errorHandler = null
+    })
+
     it('overwrites the component options with the options other than the mounting options when the options for mount contain those', () => {
       const Component = {
         template: '<div>{{ foo() }}{{ bar() }}{{ baz() }}</div>',