Remove error handler after mount

Author: eddyerburgh

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

@@ -15,10 +15,13 @@ import warnIfNoWindow from './warn-if-no-window'
 
 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 vueClass = options.localVue || createLocalVue()
@@ -35,6 +38,8 @@ export default function mount (component: Component, options: Options = {}): Vue
     throw (componentsWithError[0]._error)
   }
 
+  Vue.config.errorHandler = existingErrorHandler
+
   const wrapperOptions = {
     attachedToDocument: !!options.attachToDocument,
     sync: !!((options.sync || options.sync === undefined))

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

@@ -235,6 +235,37 @@ describeRunIf(process.env.TEST_ENV !== 'node',
       expect(fn).to.throw('Error in mounted')
     })
 
+    it.only('logs errors once after mount and restores user error handler', (done) => {
+      const TestComponent = {
+        template: '<div/>',
+        updated: function () {
+          throw new Error('Error in updated')
+        }
+      }
+
+      const wrapper = mount(TestComponent, {
+        sync: false
+      })
+      wrapper.vm.$forceUpdate()
+      setTimeout(() => {
+        expect(consoleError).calledTwice
+        done()
+      })
+    })
+
+    it.only('restores user error handler after mount', () => {
+      const existingErrorHandler = () => {}
+      Vue.config.errorHandler = existingErrorHandler
+      console.log(Vue.config.errorHandler)
+      const TestComponent = {
+        template: '<div/>'
+      }
+
+      mount(TestComponent)
+
+      expect(Vue.config.errorHandler).to.equal(existingErrorHandler)
+    })
+
     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>',