cypress/system-tests/test/page_loading_spec.js

const bodyParser = require('body-parser')
const systemTests = require('../lib/system-tests').default

let count = 0

const onServer = function (app) {
  app.use(bodyParser.json())

  app.get('/first', (req, res) => {
    // reset the count anytime we visit first again
    count = 0

    return res.send('<html><h1>first</h1><a href=\'/second\'>second</a></html>')
  })

  app.get('/second', (req, res) => {
    count += 1

    return res.send(`<html><h1>second</h1><a href='/slow'>slow</a><span id='count'>${count}</span></html>`)
  })

  app.get('/slow', (req, res) => {
    return setTimeout(() => {
      return res.send('<html><h1>slow</h1></html>')
    }
    , 2000)
  })

  app.get('/form', (req, res) => {
    return res.send(`\
<html>
<iframe src="http://localhost:17170/index.html"></iframe>
<form action="/redirected-to"></form>
</html>\
`)
  })

  app.get('/redirected-to', (req, res) => {
    return res.send(`\
<html>
<h1>I AM THE NEW PAGE</h1>
<script src="http://localhost:17170/static/jquery.js"></script>
<script>
  $.get('/cypress.json')
  $.get('/cypress.json')
  $.get('/cypress.json')
  $.get('/cypress.json')
</script>
</html>\
`)
  })

  app.post('/json', (req, res) => {
    return res.json({
      body: req.body,
    })
  })

  return app.get('/html', (req, res) => {
    return res.send('<html>content</html>')
  })
}

describe('e2e page_loading', () => {
  systemTests.setup({
    servers: [{
      port: 1717,
      onServer,
    }, {
      port: 17170,
      static: true,
    }],
  })

  // this tests that __cypress.initial is set correctly whilst navigating
  // between pages, or during cy.reload
  // additionally this creates an edge case where after __cypress.initial is
  // set we send an XHR which should not inject because its requested for JSON
  // but that another XHR which is requested for html should inject
  systemTests.it('passes', {
    spec: 'page_loading.cy.js',
    snapshot: true,
  })
})