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General Questions

General Cypress Questions

Is Cypress free and open source?

Cypress is a free, downloadable and open source (MIT license) application. This is always free to use. Cypress Cloud is a web application that offers a variety of billing plans (including a free, open source plan) for when you want to record your test runs in CI.

Please see our Pricing Page for more details.

What operating systems do you support?

You can install Cypress on Mac, Linux, and Windows. For additional information, please see our System requirements.

Do you support native mobile apps?

Cypress will never be able to run on a native mobile app, but we can test some functionality of mobile web browsers and test mobile applications that are developed in a browser, such as with the Ionic framework.

Currently you can control the viewport with the cy.viewport() command to test responsive, mobile views in a website or web application. You can also mimic certain behaviors like swiping using custom commands.

You can read about testing mobile applications with Ionic and Cypress here and see how we manage testing the mobile viewport in the Cypress Real World App.

How is this different from 'X' testing tool?

Cypress is a hybrid application/framework/service all rolled into one. It takes a little bit of other testing tools, brings them together and improves on them.

Mocha

Mocha is a testing framework for JavaScript. Mocha gives you the it, describe, beforeEach methods. Cypress isn't different from Mocha, it actually uses Mocha under the hood. All of your tests will be written on top of Mocha's bdd interface.

Karma

A unit testing runner for JavaScript, Karma, works with either Jasmine, Mocha, or any other JavaScript testing framework.

Karma also watches your JavaScript files, live reloads when they change, and is also the reporter for your tests failing / passing. It runs from the command line.

Cypress essentially replaces Karma because it does all of this already and much more.

Capybara

The Ruby specific tool that allows you to write integration tests for your web application is Capybara. In the Rails world, this is the go-to tool for testing your application. It uses Sauce Labs (or another headless driver) to interact with browsers. Its API consists of commands that query for DOM elements, perform user actions, navigate around, etc.

Cypress essentially replaces Capybara because it does all of these things and much more. The difference is that instead of testing your application in a GUI-less console, you would see your application at all times. You'd never have to take a screenshot to debug because all commands instantly provide you the state of your application while they run. Upon any command failing, you'll get a human-readable error explaining why it failed. There's no "guessing" when debugging.

Oftentimes Capybara begins to not work as well in complex JavaScript applications. Additionally, trying to TDD your application is often difficult. You often have to resort to writing your application code first (typically manually refreshing your browser after changes) until you get it working. From there you write tests, but lose the entire value of TDD.

Protractor

Using Protractor provides a nice Promise-based interface on top of Selenium, which makes it less complicated to deal with asynchronous code. Protractor comes with all of the features of Capybara and essentially suffers from the same problems.

Cypress replaces Protractor because it does all of these things and much more. One major difference is that Cypress enables you to write your unit tests and integration tests in the same tool, as opposed to splitting up this work across both Karma and Protractor.

Also, Protractor is very much focused on AngularJS, whereas Cypress is designed to work with any JavaScript framework. Protractor, because it's based on Selenium, is still pretty slow, and is prohibitive when trying to TDD your application. Cypress, on the other hand, runs at the speed your browser and application are capable of serving and rendering; there is no additional bloat.

Do you support X language or X framework?

Any and all. Ruby, Node, C#, PHP - none of that matters. Cypress tests anything that runs in the context of a browser. It is back end, front end, language and framework agnostic.

You'll write your tests in JavaScript, but beyond that Cypress works everywhere.

Can I run Cypress on another browser other than Chrome?

You can read about our currently available browsers here.

Will Cypress work in my CI provider?

Cypress works in any CI provider.

Does Cypress require me to change any of my existing code?

No. But if you're wanting to test parts of your application that are not easily testable, you'll want to refactor those situations (as you would for any testing).

Does Cypress use Selenium / Webdriver?

No. In fact Cypress' architecture is very different from Selenium in a few critical ways:

  • Cypress runs in the context of the browser. With Cypress it's easier to inspect what is running in the browser, but harder to talk to the outside world. In Selenium it's the exact opposite. Selenium runs outside of the browser where your application is running (though Cypress is adding more commands every day that give you access to the outside world - like cy.request(), cy.exec(), and cy.task()).
  • With Selenium you get either 100% simulated events (with Selenium RC) or 100% native events (with Selenium WebDriver). With Cypress, you get both. For the most part we use simulated events. However we do use automation APIs for things like Cookies where we extend outside of the JavaScript sandbox and interact with the underlying browser APIs. This gives us flexibility to determine which type of event to use in specific situations. Native event support is on our roadmap.

If Cypress runs in the browser, doesn't that mean it's sandboxed?

Yes, technically; it's sandboxed and has to follow the same rules as every other browser. That's actually a good thing because it doesn't require a browser extension, and it naturally will work across all browsers (which enables cross browser testing).

But Cypress is actually way beyond a basic JavaScript application running in the browser. It is also a desktop application and communicates with back end web services.

All of these technologies together are coordinated and enable Cypress to work, which extends its capabilities far outside of the browser sandbox. Without these, Cypress would not work at all. For the vast majority of your web development, Cypress will work fine, and already does work.

We use WebSockets; will Cypress work with that?

Yes.

We have the most complex most outrageous authentication system ever; will Cypress work with that?

If you're using some complex thumb-print, retinal-scan, time-based, key-changing, microphone, audial, decoding mechanism to log in your users, then no, Cypress won't work with that. But seriously, Cypress is a development tool, which helps you test your web applications. If your application is doing 100x things to make it extremely difficult to access, Cypress won't magically make it any easier.

Because Cypress is a development tool, you can always make your application more accessible while in your development environment. If you want, disable complex steps in your authentication systems while you're in your testing environment. After all, that's why we have different environments! Normally you already have a development environment, a testing environment, a staging environment, and a production environment. So expose the parts of your system you want accessible in each appropriate environment.

In doing so, Cypress may not be able to give you 100% coverage without you changing anything, but that's okay. Use different tools to test the less accessible parts of your application, and let Cypress test the other 99%.

Remember, Cypress won't make a non-testable application suddenly testable. It's on your shoulders to architect your code in an accessible manner.

Is it possible to use cypress on .jspa?

Yes. Cypress works on anything rendered to a browser.

Can I use Cypress to script user-actions on an external site like gmail.com?

No. There are already lots of tools to do that. Using Cypress to test against a 3rd party application is not its intended use. It may work but will defeat the purpose of why it was created. You use Cypress while you develop your application, it helps you write your tests.

Is there code coverage?

There is a plugin and detailed documentation on how to get end-to-end, unit and full stack code coverage.

You may also find the following resources helpful when writing end-to-end tests:

Are there driver bindings in my language?

Cypress does not utilize WebDriver for testing, so it does not use or have any notion of driver bindings. If your language can be somehow transpiled to JavaScript, then you can configure Cypress webpack preprocessor or Cypress Browserify preprocessor to transpile your tests to JavaScript that Cypress can run.

What resources do you recommend to learn JavaScript before writing Cypress tests?

We hope that Cypress makes test writing simple and fun, even for people with a minimal knowledge of JavaScript. If you would like to develop your JS skills, we recommend the following free online resources:

You can also learn JavaScript by watching these videos:

So what benefits would one get for converting one's unit tests from Karma or Jest to Cypress?

Unit tests are not something we are really trying to solve right now. Most of the cy API commands are useless in unit tests. The biggest benefit of writing unit tests in Cypress is that they run in a browser, which has debugger support built in.

We have internally experimented at doing DOM based component unit testing in Cypress - and that has the possibility of being an excellent "sweet spot" for unit tests. You'd get full DOM support, screenshot support, snapshot testing, and you could then use other cy commands (if need be). But as I mentioned this isn't something we're actively pushing; it remains a thing that's possible if we wanted to go down that route.

With that said - we actually believe the best form of testing in Cypress is a combination of a "unit test" mixed with an "e2e test". We don't believe in a "hands off" approach. We want you to modify the state of your application, take shortcuts as much as possible (because you have native access to all objects including your app). In other words, we want you to think in unit tests while you write integration tests.

What's the difference between a Spec, Test, and a Test Suite?

The terms spec, test, and test suite have specific meanings. Here's how they are differentiated in Cypress:

Spec A single test file that contains a set of test cases or individual tests. Each spec file typically focuses on testing a specific feature, functionality, or aspect of the application under test. Specs define the test scenarios, interactions with the application, and assertions to verify expected behavior. Spec files are written in JavaScript or TypeScript and have a .js or .ts extension.

Test An individual test case within a spec file. It represents a specific scenario or behavior that needs to be tested. A test typically consists of a series of actions performed on the application being tested, such as interacting with UI elements, submitting forms, or making assertions to validate the expected outcomes. Cypress provides a rich set of built-in commands and APIs to facilitate writing tests and interacting with the application in a declarative manner.

Test Suite A collection of spec files that are grouped together. It allows you to organize your tests based on different criteria, such as functional areas, modules, or specific features. A test suite can include multiple spec files, each containing one or more tests. By grouping related tests together in a test suite, you can organize and manage your tests more effectively. Cypress provides options to run individual spec files, multiple spec files, or the entire test suite during test execution.

Common examples are:

  • Smoke: Designed to quickly check if the basic functionalities of an application are working as expected. They are not exhaustive but aim to catch major issues early in the development process.
  • Critical path: Similar to smoke tests but are specifically focused on the critical paths or workflows within an application. They identify and test the most important user journeys or workflows that users frequently perform.
  • UI: Designed to simulate user interactions with the application's user interface. They cover a broad range of user scenarios, including navigating through different pages, interacting with UI elements, and validating the visual aspects of the application.
  • API: Focused on testing the backend or server-side of an application by making requests to its APIs (Application Programming Interfaces). These tests validate the functionality, reliability, and performance of the APIs that the application relies on.

When should I write a End-to-End tests and when should I write Component Tests?

For more information on how to choose a Cypress testing type, we recommend this Testing Types Guide.

When should I write a unit test and when should I write an end-to-end test?

We believe unit tests and end-to-end tests have differences that should guide your choice.

Unit testsEnd-to-end tests
Focus on codeFocus on the features
Should be kept shortCan be long
Examine the returned result of actionsExamine side effect of actions: DOM, storage, network, file system, database
Important to developer workflowImportant to end user's workflow

In addition to the above differences, below are a few rules of thumb to decide when to write a unit test and when to write an end-to-end test.

  • If the code you are trying to test is called from other code, use a unit test.
  • If the code is going be called from the external system, like a browser, use an end-to-end test.
  • If a unit test requires a lot of mocking and you have to bring tools like jsdom, enzyme, or sinon.js to simulate a real world environment, you may want to rewrite it as an end-to-end test.
  • If an end-to-end test does not go through the browser and instead calls the code directly, you probably want to rewrite it as a unit test

Finally, unit and end-to-end tests are not that different and have common features. Good tests:

  • Focus on and test only one thing.
  • Are flake-free and do not fail randomly.
  • Give you confidence to refactor code and add new features.
  • Are able to run both locally and on a continuous integration server.

Certainly, unit and end-to-end tests are NOT in opposition to each other and are complementary tools in your toolbox.

How do I convince my company to use Cypress?

First, be honest with yourself - is Cypress the right tool for your company and your project? We believe that the best approach is a "bottoms up" approach, where you can demonstrate how Cypress solves your company's particular needs. Implement a prototype with your project to see how it feels. Test a couple of common user stories. Identify if there are any technical blockers. Show the prototype to others before proceeding any further. If you can demonstrate the benefits of using Cypress as a developer tool for your project to other engineers, then Cypress will likely be more quickly adopted.

How can I find out about new versions of Cypress?

We publish our releases at GitHub and Npm, together with the releases we also publish a changelog with the principal changes, fixes, and updates. You can follow through these links:

How often are Cypress versions released?

We schedule releases of Cypress on Monday every two weeks. This new version includes any bugfixes and/or features that have been completed by that time. You can see all issues merged into the default code branch but not yet released by looking at the issues with the label stage: pending release.

We schedule major releases with breaking changes approximately every 3 months.

If there is a significant bug outside of our release schedule then we release a patch as soon as possible.

What information is captured or transmitted when using Cypress?

Cypress runs locally so no data is sent to Cypress aside from exception data, which can be disabled using the instructions here.

Can I write API tests using Cypress?
End-to-End Only

Cypress is mainly designed to run end-to-end and component tests, but if you need to write a few tests that call the backend API using the cy.request() command ... who can stop you?

it('adds a todo', () => {
cy.request({
url: '/todos',
method: 'POST',
body: {
title: 'Write REST API',
},
})
.its('body')
.should('deep.contain', {
title: 'Write REST API',
completed: false,
})
})

Take a look at our Real World App (RWA) that uses quite a few such tests to verify the backend APIs.

You can verify the responses using the built-in assertions and perform multiple calls. You can even write E2E tests that combine UI commands with API testing as needed:

it('adds todos', () => {
// drive the application through its UI
cy.visit('/')
cy.get('.new-todo')
.type('write E2E tests{enter}')
.type('add API tests as needed{enter}')
// now confirm the server has 2 todo items
cy.request('/todos')
.its('body')
.should('have.length', 2)
.and((items) => {
// confirm the returned items
})
})

Take a look at Add GUI to your E2E API tests blog post, then at cy-api plugin that pipes the request and response objects into Cypress GUI for easier debugging.

A good strategy for writing targeted API tests is to use them to reach the hard-to-test code not covered by other tests. You can find such places in the code using the code coverage as a guide. Watch the Ship safer code with Cypress and Codecov webinar where we show how to apply this strategy and reach the 100% fullstack code coverage via mostly E2E tests and a few targeted API and unit tests.