Fast, easy and reliable testing for anything that runs in a browser.

cypress

Learn Cypress

Imagine the following.

You join a new project and after getting access to the repo you notice that there's no tests.

You decide to ask the team whether they are in different repo or something and unfortunately the answer is:

>We don't have any tests, we didn't have the time.

😐

In this collection we're going to learn how to add e2e tests with cypress.io to an existing React app in order to do two things:

- 🌟 Ensure that our app currently works as intended
- 🌟 Allow us to add features to it with a technique called "Cypress Driven Development" 

In less than 20 minutes we're going to go through:

- ⚡️Adding cypress.io setup to an existing project
- ⚡️Testing search functionality with `data-cy` properties
- ⚡️Using "Cypress Driven Development" to add a new feature to an app
- ⚡️Use Cypress UI to debug an API response
- ⚡️How to use `cy.only` and `cy.skip` in order for us to build our e2e test suite faster

and much more!

Add e2e tests with cypress to a React application

One of the most important — but most ignored — practices for web developers is performing end-to-end testing on applications before they go live into production. You know: making sure they work like they’re supposed to. But testing can be tedious, and definitely not fun.

In this course, Brett Cassette will show you how you can test all layers of your application stack, simultaneously, with Cypress. When you use Cypress, it’s like having a robot that uses your app the way a real user would. Cypress reports if things work the way you designed them to — and if they don’t — every step of the way. And it’s fun.

After completing this course, you’ll be ready to apply the same E2E testing principles to your own applications. Stop leaning on your QA department (if it exists) to stress-test your application, and ship your app knowing it’s ready. 


Test Production Ready Apps with Cypress

The tools available for unit testing have come a long way. While testing may never be “easy”, the available tools have certainly moved testing closer to the simple end of the spectrum. Full end to end testing hasn’t quite kept the same pace and as a result many applications are testing manually and often by users in production. Cypress provides a testing environment that makes end-to-end testing fast and reliable with a simple API that makes creating automated unit tests for your web applications a no-brainer.


End to End testing with Cypress

Your app can react in various way on different network conditions. Cypress has a great toolset for setting up those conditions, which enable you to test your app thoroughly. That way you can ship your app with confidence.

Cypress’ .intercept() command is one of the most fun command to use. And it’s also one of the most useful.

Especially when you are done with all your happy paths and want to increase your test coverage with some edge cases.

These edge cases can mean different data, headers or server behavior. You can modify all of these, dynamically or with a static fixture prepared beforehand

Test Network Edge Cases with cy.intercept() Command in Cypress

Web accessibility (also referred to as a11y) is the design and creation of websites that can be used by everyone. Accessibility support is necessary to allow assistive technology to interpret web pages.

React fully supports building accessible websites, often by using standard HTML techniques.

Erin Doyle is an expert in creating accessible React applications and has developed a course that will give you a concrete process for auditing react apps for accessibility. In this course, you will go through different tools and libraries to audit components in a React app.

Auditing React Apps for Accessibility 

Adding Cypress to a project is a simple npm install away. We won’t need any global dependencies beyond node and npm to get started with Cypress. In this lesson we’ll look at our existing application, add Cypress as a dev dependency with npm and fire it up for the first time to have a look around.

Add Cypress to an Existing Application with npm

In order to test our application, Cypress will need to visit it in the browser. In this lesson we’ll see how we can visit our application with Cypress and how to configure a baseUrl for Cypress to make that even easier.

Visit a page with Cypress

In this lesson, we’ll add tests that finds a focused input. We’ll use Chrome’s dev tools from inside the Cypress runner to inspect the element and update our test to verify that the expected element is focused. We’ll see how Cypress can be used to test drive our application by creating a failing test and updating our application code to make it pass.


Find and Test Focused Input with Chrome’s DevTools in Cypress

React based applications often use controlled inputs, meaning the input event leads to the application code setting the value of the very input we’re typing into. Since this moves the input setting behavior into the application code, we should have a test to guard against future changes that might break this behavior. In this lesson, we’ll use the Selector Playground feature in Cypress and create a test that enters text into an input and asserts that the value is the same as the entered text.

Test React’s Controlled Input with Cypress Selector Playground

A lot of our tests will share setup steps. Since Cypress is using Mocha under the hood, we can take advantage of existing features such as the ability to define a `beforeEach` block that runs before each of our tests. In this lesson we’ll refactor two tests that contain duplicate commands by moving that duplication into the `beforeEach` for our `describe` block.


Reduce Code Duplication in Cypress Tests with beforeEach

To keep our tests fast and easily repeatable, it makes sense to create many integration tests and fewer full end-to-end tests. In this lesson, we’ll see how to stub out network requests to create repeatable integration tests by ensuring our application runs in a known state for our tests.


Stub Network Requests in a Cypress Test

When creating integration tests with Cypress, we’ll often want to stub network requests that respond with large datasets. All of this mock data can lead to test code that is hard to read. In this lesson, we’ll see how to use fixtures to keep sample data in files and easily load it on demand in your tests.

Load Data from Test Fixtures in Cypress

When testing interactions that require asynchronous calls, we’ll need to wait on responses to make sure we’re asserting about the application state at the right time. With Cypress, we don’t have to use arbitrary time periods to wait. In this lesson, we’ll see how to use an alias for a network request and wait for it to complete without having to wait longer than required or guess at the duration.

Wait for XHR Responses in a Cypress Test

Cypress provides a straightforward API that allows you to define custom commands. In this lesson, we’ll take a series of Cypress commands and wrap them up in a single custom command so we can easily repeat these steps in multiple specs.

Create a Single Custom Cypress Command from Multiple Commands

In this lesson well stub a `POST` request and use Cypress commands to fill in and submit a form. We’ll wait for the submission to resolve and then assert that the new item was added to the list.

Stub a Post Request for Successful Form Submission with Cypress

Testing your application’s behavior when an XHR call results in an error can be difficult. The use of stubs for XHR calls makes it easy for us to setup failure scenarios and ensure that our front-end responds the way we expect. In this lesson, we’ll stub a 500 response for a form submission and verify that our application responds appropriately. 

Test XHR Failure Conditions with Cypress

We often only show UI elements as a result of some user interaction. Cypress detects visibility and by default won’t allow your test to interact with an element that isn’t visible. In this lesson, we’ll work with a button that is shown on hover and see how you can either bypass the visibility restriction or use Cypress to update the state of your application, making items visible prior to interacting with them.

Interact with Hidden Elements in a Cypress Test

We’ll often need to access the same DOM elements multiple times in one test. Your first instinct might be to use `cy.get` and assign the result to a variable for reuse. This might appear to work fine at first, but can lead to trouble. Everything in Cypress is done asynchronously and you’re interacting with an application’s DOM, which is changing as your tests interact with it. In this lesson, we’ll see how we can reference DOM elements in multiple places with the alias feature in Cypress.

Create Aliases for DOM Elements in Cypress Tests

Many applications have features that can be used with slight variations. Instead of maintaining multiple tests with nearly identical code, we can take advantage of the JavaScript runtime and use normal data structures and plain old JavaScript to test and make assertions for multiple interactions in a single test.

Test Variations of a Feature in Cypress with a data-driven Test

Testing is a great way to find and prevent future issues. Cypress takes this to the next level with a UI that gives you access to step-by-step logs of your test run as well as direct access to Chrome’s devTools. In this lesson, we’ll introduce a logic error and use the Cypress UI to track down and fix our bug.

Access step-by-step Logs with Chrome devTools and Cypress UI

Integration tests let us keep our tests fast and reliable. They also allow us to test scenarios that are hard to recreate in a full end-to-end setup. That being said, we should round out our test suite with some high-level smoke tests. In this lesson, we’ll create some tests that seed our data-source and avoid stubbing our network calls, allowing us to test all parts of the application while using known data to keep our tests flake-free.

Cypress