test: Add test for handling client error in _error

Author: okmttdhr

test/integration/error-in-error-client/pages/_error.js

@@ -0,0 +1,23 @@
+import React from 'react'
+
+class Error extends React.Component {
+  static async getInitialProps({ res, err }) {
+    const statusCode = res ? res.statusCode : err ? err.statusCode : null
+    return { statusCode }
+  }
+
+  render() {
+    if (typeof window !== 'undefined') {
+      throw new Error('Error from Error page')
+    }
+    return (
+      <p>
+        {this.props.statusCode
+          ? `An error ${this.props.statusCode} occurred on server`
+          : 'An error occurred on client'}
+      </p>
+    )
+  }
+}
+
+export default Error

test/integration/error-in-error-client/pages/index.js

@@ -0,0 +1,21 @@
+import Link from 'next/link'
+
+function Index() {
+  return (
+    <>
+      <h3>Hi 👋</h3>
+      <Link href="/a-non-existing-page">
+        <a>a link to no-where</a>
+      </Link>
+    </>
+  )
+}
+
+Index.getInitialProps = () => {
+  if (typeof window !== 'undefined') {
+    throw new Error('Error from Index page')
+  }
+  return {}
+}
+
+export default Index

test/integration/error-in-error-client/test/index.test.js

@@ -0,0 +1,33 @@
+/* eslint-env jest */
+
+import path from 'path'
+import webdriver from 'next-webdriver'
+import {
+  nextBuild,
+  nextStart,
+  findPort,
+  killApp,
+  waitFor,
+} from 'next-test-utils'
+
+jest.setTimeout(1000 * 60 * 1)
+const appDir = path.join(__dirname, '..')
+let app
+let port
+
+describe('Handles an Error in _error', () => {
+  beforeAll(async () => {
+    await nextBuild(appDir)
+    port = await findPort()
+    app = await nextStart(appDir, port)
+  })
+  afterAll(() => killApp(app))
+
+  it('Handles error during client transition', async () => {
+    const browser = await webdriver(port, '/')
+    await browser.waitForElementByCss('a').click()
+    await waitFor(1000)
+    const html = await browser.eval('document.body.innerHTML')
+    expect(html).toMatch(/internal server error/i)
+  })
+})