cypress-network-idle

A little Cypress.io plugin for waiting for network to be idle before continuing with the test

Videos

• Cypress-network-idle plugin
• Prepare Intercept And Wait Using cypress-network-idle Plugin

Study

Covered in my course 🎓 Cypress Network Testing

Install

# install using NPM
npm i -D cypress-network-idle
# install using Yarn
yarn add -D cypress-network-idle

Import or require this plugin from the support file or from the spec file

import 'cypress-network-idle'

Use

Wait for two seconds to pass without any network calls (Ajax, static resources)

cy.waitForNetworkIdle(2000)

Wait one second without any GET calls to /v1/api endpoint

cy.waitForNetworkIdle('/v1/api', 1000)

Wait for 5 seconds without any POST calls to /graphql endpoint

cy.waitForNetworkIdle('POST', '/graphql', 5000)

Wait for 5 seconds for any call (GET, POST, PUT, etc) to any endpoint

cy.waitForNetworkIdle('*', '*', 5000)

Wait for 5 seconds for any POST or GET to any endpoint

cy.waitForNetworkIdle('+(POST|GET)', '*', 5000)

For pattern matching see more examples in the cy.intercept() documentation.

No logging

You can disable the log messages by adding option object with { log: false } property

cy.waitForNetworkIdle('/v1/api', 1000, { log: false })

Separate prepare

Sometimes the network calls start early. For example, if the network calls are kicked off by the cy.visit you want to start capturing the timestamps before it, but wait for the network to be idle after. You can start listening using the prepare call like this.

cy.waitForNetworkIdlePrepare({
  method: 'GET',
  pattern: '*',
  alias: 'calls',
})
cy.visit('/')
// now wait for the "@calls" to finish
cy.waitForNetworkIdle('@calls', 1000)

Notice the use of the alias parameter to correctly listen to the intercepted calls. You can disable logging by adding log: false to the prepare call

cy.waitForNetworkIdlePrepare({
  method: 'GET',
  pattern: '*',
  alias: 'calls',
  log: false,
})

You can wait multiple times for the prepared network alias.

cy.waitForNetworkIdlePrepare({
  method: 'POST',
  pattern: '/api/graphql',
  alias: 'graphql',
})
cy.visit('/')
cy.waitForNetworkIdle('@graphql', 1000)
// the page has fully loaded
// interact with the page
cy.waitForNetworkIdle('@graphql', 1000)
// the page has finished additional processing

fail on error status code

By default, the network calls might fail and the test happily continues. You can make the idle spy fail if any of the matching network calls return 4xx or 5xx errors. These classes of error status code have their own flag to enable.

fail on 4xx

// fail the test if any of the matching calls
// returns a 4xx status code
cy.waitForNetworkIdlePrepare({
  method: '*',
  alias: 'all',
  pattern: '**',
  failOn4xx: true,
})

fail on 5xx

// fail the test if any of the matching calls
// returns a 5xx status code
cy.waitForNetworkIdlePrepare({
  method: '*',
  alias: 'all',
  pattern: '**',
  failOn5xx: true,
})

failOn

You can write your own callback function failOn(req, res) to decide if the network call should fail the test. Can be useful to include additional information in the error message. For example, let's include the custom message headers:

cy.waitForNetworkIdlePrepare({
  method: 'POST',
  alias: 'post',
  pattern: '/status-401',
  failOn(req, res) {
    if (res.statusCode === 401) {
      return `Call ${req.method} ${req.url} (x flag ${req.headers['x-my-flag']}) failed`
    }
  },
})

All you need to do to fail the test is return an error message from the synchronous callback.

Multiple registrations

If you try to register the same intercept method, pattern, and alias multiple times, only a single first registration will be made.

cy.waitForNetworkIdlePrepare({
  method: 'GET',
  pattern: '/user',
  alias: 'user',
})
// this registration will be ignored
cy.waitForNetworkIdlePrepare({
  method: 'GET',
  pattern: '/user',
  alias: 'user',
})
// this registration will be ignored
cy.waitForNetworkIdlePrepare({
  method: 'GET',
  pattern: '/user',
  alias: 'user',
})

Pending calls

If there are ongoing network calls, this plugin waits for them to resolve before checking for network idle, see the after.js spec.

Yields

The command yields an object with a few timestamps and the number of network calls. See the src/index.d.ts for precise fields

cy.waitForNetworkIdle(2000)
  // check how long the command waited
  .its('waited')
  // it should have waited for at least 2 seconds
  // but could be up to 3 seconds if the app
  // made a call one second after the start
  .should('be.within', 2000, 3000)

Limit the intercept

You can limit which requests to consider by using method and pattern parameters. For example, see the spec get-vs-post.js

// listen to all POST calls
cy.waitForNetworkIdlePrepare({
  method: 'POST',
  pattern: '*',
  alias: 'postCalls',
})

cy.visit('/get-vs-post')
cy.waitForNetworkIdle('@postCalls', 2000)

// listen to "POST /add-user" calls
cy.waitForNetworkIdlePrepare({
  method: 'POST',
  pattern: '/add-user',
  alias: 'addUser',
})

cy.visit('/get-vs-post')
cy.waitForNetworkIdle('@addUser', 2000)

Overwrite commands

If you always want to want for network idle when calling cy.visit you can overwrite this command using the provided code in src/register.js file

// your spec
const { registerVisit } = require('cypress-network-idle/src/register')
registerVisit({ timeout: 1000 })

it('waits for network idle', () => {
  cy.visit('/')
  // the network has been idle for 1 second
})

Types

This plugin includes the TypeScript types, import them from your JavaScript files using the reference types comment or via TS config.

/// <reference types="cypress-network-idle" />

Discussion

This plugin uses the timestamp of the request and the response to compute the idle timestamp. This helps with any longer-running requests - the idle time is computed from their completion.

Small print

Author: Gleb Bahmutov <[email protected]> © 2021

• @bahmutov
• glebbahmutov.com
• blog
• videos
• presentations
• cypress.tips

License: MIT - do anything with the code, but don't blame me if it does not work.

Support: if you find any problems with this module, email / tweet / open issue on Github

MIT License

Copyright (c) 2021 Gleb Bahmutov <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.