Add with-cypress example (#27900)

This PR adds a with-cypress example to match the examples in upcoming docs. 

## Documentation / Examples

- [ ] Make sure the linting passes

**Note:** This PR does not pass linting because ESLint needs to have the [eslint-plugin-cypress](https://github.com/cypress-io/eslint-plugin-cypress) installed globally to ignore the Cypress methods.

examples/with-cypress/.gitignore

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+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# vercel
+.vercel

examples/with-cypress/README.md

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+# Next.js + Cypress
+
+This example shows how to configure Cypress to work with Next.js.
+
+## Preview
+
+Preview the example live on [StackBlitz](http://stackblitz.com/):
+
+[![Open in StackBlitz](https://developer.stackblitz.com/img/open_in_stackblitz.svg)](https://stackblitz.com/github/vercel/next.js/tree/canary/examples/with-cypress)
+
+## Deploy your own
+
+Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example):
+
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/git/external?repository-url=https://github.com/vercel/next.js/tree/canary/examples/with-cypress&project-name=with-cypress&repository-name=with-cypress)
+
+## How to use
+
+Execute [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app) with [npm](https://docs.npmjs.com/cli/init) or [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/) to bootstrap the example:
+
+```bash
+npx create-next-app --example with-cypress with-cypress-app
+# or
+yarn create next-app --example with-cypress with-cypress-app
+```
+
+Deploy it to the cloud with [Vercel](https://vercel.com/new?utm_source=github&utm_medium=readme&utm_campaign=next-example) ([Documentation](https://nextjs.org/docs/deployment)).

examples/with-cypress/cypress.json

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+{
+  "baseUrl": "http://localhost:3000"
+}

examples/with-cypress/cypress/fixtures/example.json

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+{
+  "name": "Using fixtures to represent data",
+  "email": "hello@cypress.io",
+  "body": "Fixtures are a great way to mock data for responses to routes"
+}

examples/with-cypress/cypress/integration/app.spec.js

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+/* eslint-disable */
+// Disable ESLint to prevent failing linting inside the Next.js repo.
+// If you're using ESLint on your project, we recommend installing the ESLint Cypress plugin instead:
+// https://github.com/cypress-io/eslint-plugin-cypress
+
+describe('Navigation', () => {
+  it('should navigate to the about page', () => {
+    // Start from the index page
+    cy.visit('http://localhost:3000/')
+
+    // Find a link with an href attribute containing "about" and click it
+    cy.get('a[href*="about"]').click()
+
+    // The new url should include "/about"
+    cy.url().should('include', '/about')
+
+    // The new page should contain an h1 with "About page"
+    cy.get('h1').contains('About Page')
+  })
+})

examples/with-cypress/cypress/plugins/index.js

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+/// <reference types="cypress" />
+// ***********************************************************
+// This example plugins/index.js can be used to load plugins
+//
+// You can change the location of this file or turn off loading
+// the plugins file with the 'pluginsFile' configuration option.
+//
+// You can read more here:
+// https://on.cypress.io/plugins-guide
+// ***********************************************************
+
+// This function is called when a project is opened or re-opened (e.g. due to
+// the project's config changing)
+
+/**
+ * @type {Cypress.PluginConfig}
+ */
+// eslint-disable-next-line no-unused-vars
+module.exports = (on, config) => {
+  // `on` is used to hook into various events Cypress emits
+  // `config` is the resolved Cypress config
+}

examples/with-cypress/cypress/support/commands.js

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+// ***********************************************
+// This example commands.js shows you how to
+// create various custom commands and overwrite
+// existing commands.
+//
+// For more comprehensive examples of custom
+// commands please read more here:
+// https://on.cypress.io/custom-commands
+// ***********************************************
+//
+//
+// -- This is a parent command --
+// Cypress.Commands.add('login', (email, password) => { ... })
+//
+//
+// -- This is a child command --
+// Cypress.Commands.add('drag', { prevSubject: 'element'}, (subject, options) => { ... })
+//
+//
+// -- This is a dual command --
+// Cypress.Commands.add('dismiss', { prevSubject: 'optional'}, (subject, options) => { ... })
+//
+//
+// -- This will overwrite an existing command --
+// Cypress.Commands.overwrite('visit', (originalFn, url, options) => { ... })

examples/with-cypress/cypress/support/index.js

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+// ***********************************************************
+// This example support/index.js is processed and
+// loaded automatically before your test files.
+//
+// This is a great place to put global configuration and
+// behavior that modifies Cypress.
+//
+// You can change the location of this file or turn off
+// automatically serving support files with the
+// 'supportFile' configuration option.
+//
+// You can read more here:
+// https://on.cypress.io/configuration
+// ***********************************************************
+
+// Import commands.js using ES2015 syntax:
+import './commands'
+
+// Alternatively you can use CommonJS syntax:
+// require('./commands')

examples/with-cypress/package.json

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+{
+  "name": "with-cypress",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start",
+    "cypress": "cypress open",
+    "cypress:headless": "cypress run",
+    "e2e": "start-server-and-test dev http://localhost:3000 cypress",
+    "e2e:headless": "start-server-and-test dev http://localhost:3000 cypress:headless"
+  },
+  "dependencies": {
+    "next": "latest",
+    "react": "17.0.2",
+    "react-dom": "17.0.2"
+  },
+  "devDependencies": {
+    "cypress": "8.2.0",
+    "start-server-and-test": "1.13.1"
+  }
+}

examples/with-cypress/pages/_app.js

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+import '../styles/globals.css'
+
+function MyApp({ Component, pageProps }) {
+  return <Component {...pageProps} />
+}
+
+export default MyApp

examples/with-cypress/pages/about.js

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+import styles from '../styles/Home.module.css'
+import Link from 'next/link'
+
+export default function About() {
+  return (
+    <div className={styles.container}>
+      <main className={styles.main}>
+        <h1>About Page</h1>
+        <p className={styles.description}>
+          <Link href="/">
+            <a>&larr; Go Back</a>
+          </Link>
+        </p>
+      </main>
+    </div>
+  )
+}

examples/with-cypress/pages/index.js

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+import Head from 'next/head'
+import Image from 'next/image'
+import Link from 'next/link'
+import styles from '../styles/Home.module.css'
+
+export default function Home() {
+  return (
+    <div className={styles.container}>
+      <Head>
+        <title>Create Next App</title>
+        <meta name="description" content="Generated by create next app" />
+        <link rel="icon" href="/favicon.ico" />
+      </Head>
+
+      <main className={styles.main}>
+        <h1 className={styles.title}>
+          Welcome to <a href="https://nextjs.org">Next.js!</a>
+        </h1>
+
+        <p className={styles.description}>
+          Get started by editing{' '}
+          <code className={styles.code}>pages/index.js</code>
+        </p>
+
+        <div className={styles.grid}>
+          <Link href="/about">
+            <a className={styles.card}>
+              <h2>About Page &rarr;</h2>
+              <p>Cypress will test if this link is working.</p>
+            </a>
+          </Link>
+
+          <a href="https://nextjs.org/docs" className={styles.card}>
+            <h2>Documentation &rarr;</h2>
+            <p>Find in-depth information about Next.js features and API.</p>
+          </a>
+
+          <a href="https://nextjs.org/learn" className={styles.card}>
+            <h2>Learn &rarr;</h2>
+            <p>Learn about Next.js in an interactive course with quizzes!</p>
+          </a>
+
+          <a
+            href="https://github.com/vercel/next.js/tree/master/examples"
+            className={styles.card}
+          >
+            <h2>Examples &rarr;</h2>
+            <p>Discover and deploy boilerplate example Next.js projects.</p>
+          </a>
+
+          <a
+            href="https://vercel.com/new?utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
+            className={styles.card}
+          >
+            <h2>Deploy &rarr;</h2>
+            <p>
+              Instantly deploy your Next.js site to a public URL with Vercel.
+            </p>
+          </a>
+        </div>
+      </main>
+
+      <footer className={styles.footer}>
+        <a
+          href="https://vercel.com?utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Powered by{' '}
+          <span className={styles.logo}>
+            <Image src="/vercel.svg" alt="Vercel Logo" width={72} height={16} />
+          </span>
+        </a>
+      </footer>
+    </div>
+  )
+}