Add a set of test cases for error recovery in the dev mode (#3895)

* Add specific test cases for Error Recovery.

* Update hmr/about.js

* Add a test case: should recover after a bad return from the render function

* Add test case: should recover from errors in getInitialProps in client

* Add test case: should recover after an error reported via SSR

* Add a test case: should recover from 404 after a page has been added

* Refactor code base.

test/integration/basic/pages/hmr/about.js

@@ -1,7 +1,9 @@
-export default () => (
-  <div className='hmr-about-page'>
-    <p>
-      This is the about page.
-    </p>
-  </div>
-)
+export default () => {
+  return (
+    <div className='hmr-about-page'>
+      <p>
+        This is the about page.
+      </p>
+    </div>
+  )
+}

test/integration/basic/pages/hmr/error-in-gip.js

@@ -0,0 +1,11 @@
+import React from 'react'
+export default class extends React.Component {
+  static getInitialProps () {
+    const error = new Error('an-expected-error-in-gip')
+    throw error
+  }
+
+  render () {
+    return (<div>Hello</div>)
+  }
+}

test/integration/basic/pages/hmr/index.js

@@ -0,0 +1,7 @@
+import Link from 'next/link'
+
+export default () => (
+  <div>
+    <Link href='/hmr/error-in-gip'><a id='error-in-gip-link'>Bad Page</a></Link>
+  </div>
+)

test/integration/basic/test/error-recovery.js

@@ -0,0 +1,211 @@
+/* global describe, it, expect */
+import webdriver from 'next-webdriver'
+import { join } from 'path'
+import { check, File } from 'next-test-utils'
+
+export default (context, render) => {
+  describe('Error Recovery', () => {
+    it('should detect syntax errors and recover', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/about')
+      const text = await browser
+        .elementByCss('p').text()
+      expect(text).toBe('This is the about page.')
+
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('</div>', 'div')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /Unterminated JSX contents/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the about page/
+      )
+
+      browser.close()
+    })
+
+    it('should show the error on all pages', async () => {
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('</div>', 'div')
+
+      const browser = await webdriver(context.appPort, '/hmr/contact')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /Unterminated JSX contents/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the contact page/
+      )
+
+      browser.close()
+    })
+
+    it('should detect runtime errors on the module scope', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/about')
+      const text = await browser
+        .elementByCss('p').text()
+      expect(text).toBe('This is the about page.')
+
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('export', 'aa=20;\nexport')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /aa is not defined/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the about page/
+      )
+
+      browser.close()
+    })
+
+    it('should recover from errors in the render function', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/about')
+      const text = await browser
+        .elementByCss('p').text()
+      expect(text).toBe('This is the about page.')
+
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('return', 'throw new Error("an-expected-error");\nreturn')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /an-expected-error/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the about page/
+      )
+
+      browser.close()
+    })
+
+    it('should recover after exporting an invalid page', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/about')
+      const text = await browser
+        .elementByCss('p').text()
+      expect(text).toBe('This is the about page.')
+
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('export default', 'export default "not-a-page"\nexport const fn = ')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /The default export is not a React Component/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the about page/
+      )
+
+      browser.close()
+    })
+
+    it('should recover after a bad return from the render function', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/about')
+      const text = await browser
+        .elementByCss('p').text()
+      expect(text).toBe('This is the about page.')
+
+      const aboutPage = new File(join(__dirname, '../', 'pages', 'hmr', 'about.js'))
+      aboutPage.replace('export default', 'export default () => /search/ \nexport const fn = ')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /Objects are not valid as a React child/
+      )
+
+      aboutPage.restore()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This is the about page/
+      )
+
+      browser.close()
+    })
+
+    it('should recover from errors in getInitialProps in client', async () => {
+      const browser = await webdriver(context.appPort, '/hmr')
+      await browser.elementByCss('#error-in-gip-link').click()
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /an-expected-error-in-gip/
+      )
+
+      const erroredPage = new File(join(__dirname, '../', 'pages', 'hmr', 'error-in-gip.js'))
+      erroredPage.replace('throw error', 'return {}')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /Hello/
+      )
+
+      erroredPage.restore()
+      browser.close()
+    })
+
+    it('should recover after an error reported via SSR', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/error-in-gip')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /an-expected-error-in-gip/
+      )
+
+      const erroredPage = new File(join(__dirname, '../', 'pages', 'hmr', 'error-in-gip.js'))
+      erroredPage.replace('throw error', 'return {}')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /Hello/
+      )
+
+      erroredPage.restore()
+      browser.close()
+    })
+
+    it('should recover from 404 after a page has been added', async () => {
+      const browser = await webdriver(context.appPort, '/hmr/new-page')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /This page could not be found/
+      )
+
+      // Add the page
+      const newPage = new File(join(__dirname, '../', 'pages', 'hmr', 'new-page.js'))
+      newPage.write('export default () => (<div>the-new-page</div>)')
+
+      await check(
+        () => browser.elementByCss('body').text(),
+        /the-new-page/
+      )
+
+      newPage.delete()
+      browser.close()
+    })
+  })
+}

test/integration/basic/test/hmr.js

@@ -2,109 +2,10 @@
 import webdriver from 'next-webdriver'
 import { readFileSync, writeFileSync, renameSync } from 'fs'
 import { join } from 'path'
-import { waitFor } from 'next-test-utils'
-
-async function check (contentFn, regex) {
-  while (true) {
-    try {
-      const newContent = await contentFn()
-      if (regex.test(newContent)) break
-      await waitFor(1000)
-    } catch (ex) {}
-  }
-}
+import { waitFor, check } from 'next-test-utils'
 
 export default (context, render) => {
   describe('Hot Module Reloading', () => {
-    describe('errors', () => {
-      it('should detect syntax errors and recover', async () => {
-        const browser = await webdriver(context.appPort, '/hmr/about')
-        const text = await browser
-          .elementByCss('p').text()
-        expect(text).toBe('This is the about page.')
-
-        const aboutPagePath = join(__dirname, '../', 'pages', 'hmr', 'about.js')
-
-        const originalContent = readFileSync(aboutPagePath, 'utf8')
-        const erroredContent = originalContent.replace('</div>', 'div')
-
-        // change the content
-        writeFileSync(aboutPagePath, erroredContent, 'utf8')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /Unterminated JSX contents/
-        )
-
-        // add the original content
-        writeFileSync(aboutPagePath, originalContent, 'utf8')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /This is the about page/
-        )
-
-        browser.close()
-      })
-
-      it('should show the error on all pages', async () => {
-        const aboutPagePath = join(__dirname, '../', 'pages', 'hmr', 'about.js')
-
-        const originalContent = readFileSync(aboutPagePath, 'utf8')
-        const erroredContent = originalContent.replace('</div>', 'div')
-
-        // change the content
-        writeFileSync(aboutPagePath, erroredContent, 'utf8')
-
-        const browser = await webdriver(context.appPort, '/hmr/contact')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /Unterminated JSX contents/
-        )
-
-        // add the original content
-        writeFileSync(aboutPagePath, originalContent, 'utf8')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /This is the contact page/
-        )
-
-        browser.close()
-      })
-
-      it('should detect runtime errors on the module scope', async () => {
-        const browser = await webdriver(context.appPort, '/hmr/about')
-        const text = await browser
-          .elementByCss('p').text()
-        expect(text).toBe('This is the about page.')
-
-        const aboutPagePath = join(__dirname, '../', 'pages', 'hmr', 'about.js')
-
-        const originalContent = readFileSync(aboutPagePath, 'utf8')
-        const erroredContent = originalContent.replace('export', 'aa=20;\nexport')
-
-        // change the content
-        writeFileSync(aboutPagePath, erroredContent, 'utf8')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /aa is not defined/
-        )
-
-        // add the original content
-        writeFileSync(aboutPagePath, originalContent, 'utf8')
-
-        await check(
-          () => browser.elementByCss('body').text(),
-          /This is the about page/
-        )
-
-        browser.close()
-      })
-    })
-
     describe('delete a page and add it back', () => {
       it('should load the page properly', async () => {
         const browser = await webdriver(context.appPort, '/hmr/contact')

test/integration/basic/test/index.test.js

@@ -13,6 +13,7 @@ import {
 import rendering from './rendering'
 import clientNavigation from './client-navigation'
 import hmr from './hmr'
+import errorRecovery from './error-recovery'
 import dynamic from './dynamic'
 import asset from './asset'
 
@@ -62,5 +63,6 @@ describe('Basic Features', () => {
   clientNavigation(context, (p, q) => renderViaHTTP(context.appPort, p, q))
   dynamic(context, (p, q) => renderViaHTTP(context.appPort, p, q))
   hmr(context, (p, q) => renderViaHTTP(context.appPort, p, q))
+  errorRecovery(context, (p, q) => renderViaHTTP(context.appPort, p, q))
   asset(context)
 })

test/lib/next-test-utils.js

@@ -5,6 +5,7 @@ import express from 'express'
 import path from 'path'
 import portfinder from 'portfinder'
 import { spawn } from 'child_process'
+import { readFileSync, writeFileSync, existsSync, unlinkSync } from 'fs'
 import fkill from 'fkill'
 
 import server from '../../dist/server/next'
@@ -146,3 +147,40 @@ export async function startStaticServer (dir) {
   await promiseCall(server, 'listen')
   return server
 }
+
+export async function check (contentFn, regex) {
+  while (true) {
+    try {
+      const newContent = await contentFn()
+      if (regex.test(newContent)) break
+      await waitFor(1000)
+    } catch (ex) {}
+  }
+}
+
+export class File {
+  constructor (path) {
+    this.path = path
+    this.originalContent = existsSync(this.path) ? readFileSync(this.path, 'utf8') : null
+  }
+
+  write (content) {
+    if (!this.originalContent) {
+      this.originalContent = content
+    }
+    writeFileSync(this.path, content, 'utf8')
+  }
+
+  replace (pattern, newValue) {
+    const newContent = this.originalContent.replace(pattern, newValue)
+    this.write(newContent)
+  }
+
+  delete () {
+    unlinkSync(this.path)
+  }
+
+  restore () {
+    this.write(this.originalContent)
+  }
+}