> A little helper to unit test React components in the open source [Cypress.io](https://www.cypress.io/) test runner **v7.0.0+** **Jump to:** [Comparison](#comparison), [Blog posts](#blog-posts), [Install](#install), Examples: [basic](#basic-examples), [advanced](#advanced-examples), [full](#full-examples), [external](#external-examples), [Style options](#options), [Code coverage](#code-coverage), [Visual testing](#visual-testing), [Common problems](#common-problems), [Chat](#chat) ## TLDR - What is this? This package allows you to use [Cypress](https://www.cypress.io/) test runner to unit test your React components with zero effort. Here is a typical component testing, notice there is not external URL shown, since it is mounting the component directly. ![Example component test](images/dynamic.gif) - How is this different from [Enzyme](https://github.com/airbnb/enzyme) or [RTL](https://testing-library.com/docs/react-testing-library/intro)? It is similar in functionality BUT runs the component in the real browser with full power of Cypress E2E test runner: [live GUI, full API, screen recording, CI support, cross-platform](https://www.cypress.io/features/), and [visual testing](https://on.cypress.io/visual-testing). - If you like using `@testing-library/react`, you can use `@testing-library/cypress` for the same `findBy`, `queryBy` commands, see one of the examples in the list below - Read [My Vision for Component Tests in Cypress](https://glebbahmutov.com/blog/my-vision-for-component-tests/) by Gleb Bahmutov ## Comparison Feature | Jest / Enzyme / RTL | Cypress + `@cypress/react` --- | --- | --- Test runs in real browser | ❌ | ✅ Supports shallow mount | ✅ | ❌ Supports full mount | ✅ | ✅ Test speed | 🏎 | [as fast as the app works in the browser](#fast-enough) Test can use additional plugins | maybe | use any [Cypress plugin](https://on.cypress.io/plugins) Test can interact with component | synthetic limited API | use any [Cypress command](https://on.cypress.io/api) Test can be debugged | via terminal and Node debugger | use browser DevTools Built-in time traveling debugger | ❌ | Cypress time traveling debugger Re-run tests on file or test change | ✅ | ✅ Test output on CI | terminal | terminal, screenshots, videos Tests can be run in parallel | ✅ | ✅ via [parallelization](https://on.cypress.io/parallelization) Test against interface | if using `@testing-library/react` | ✅ and can use `@testing-library/cypress` Spying and stubbing methods | Jest mocks | [Sinon library](https://on.cypress.io/stubs-spies-and-clocks) Stubbing imports | ✅ | ✅ Stubbing clock | ✅ | ✅ Code coverage | ✅ | ✅ If you are coming from Jest + RTL world, read [Test The Interface Not The Implementation](https://glebbahmutov.com/blog/test-the-interface/). If you are coming from Enzyme world, check out the [enzyme](cypress/component/basic/enzyme) example. ## Blog posts - [My Vision for Component Tests in Cypress](https://glebbahmutov.com/blog/my-vision-for-component-tests/) - [Unit Testing React components with Cypress](https://itnext.io/unit-testing-react-components-with-cypress-4d4cf8cd59a0) - [Test React Component with @cypress/react Example](https://dev.to/bahmutov/test-react-component-with-cypress-react-unit-test-example-4d99) - [Tic-Tac-Toe Component Tests](https://glebbahmutov.com/blog/tic-tac-toe-component-tests/) - [Using .env and .env.test from React component tests](https://medium.com/@bahmutov/using-env-and-env-test-from-react-component-tests-c11aa2040bc8) - [Visual testing for React components using open source tools](https://glebbahmutov.com/blog/open-source-visual-testing-of-components/) - [12 Recipes for testing React applications using @cypress/react](https://dev.to/bahmutov/12-recipes-for-testing-react-applications-using-cypress-react-unit-test-46g6) (compare to [12 Recipes for testing React applications using Testing Library](https://dev.to/jooforja/12-recipes-for-testing-react-applications-using-testing-library-1bh2#portal)) - [Cypress Unit Testing React Components With TypeScript](https://medium.com/swlh/cypress-unit-testing-react-components-with-typescript-77b38e5043b3) - [Test The Interface Not The Implementation](https://glebbahmutov.com/blog/test-the-interface/) compares Jest + React Testing Library to @cypress/react + Cypress Testing Library - [Components People Test](https://glebbahmutov.com/blog/components-people-test/) about testing a component inside a Next.js-powered blog ## Install Requires [Node](https://nodejs.org/en/) version 12 or above. ```sh npm install --save-dev cypress @cypress/react @cypress/webpack-dev-server ``` ## Init You can use our command line wizard to give you instructions on configuring this plugin. It will try to determine which framework or bundling tool you are using and give you instructions on right configuration. ```sh npx create-cypress-tests --component-tests ``` Or continue with manual installation in the plugin file 1. Tell Cypress how your React application is transpiled or bundled (using Webpack), so Cypress can load your components. For example, if you use `react-scripts` (even after ejecting) do: ```js // cypress/plugins/index.js module.exports = (on, config) => { require('@cypress/react/plugins/react-scripts')(on, config) // IMPORTANT to return the config object // with the any changed environment variables return config } ``` See [Recipes](./docs/recipes.md) for more examples. 2. You can specify where component spec files are located. For example, to have them located in `src` folder use: ```json { "componentFolder": "src" } ``` ## API - `mount` is the most important function, allows to mount a given React component as a mini web application and interact with it using Cypress commands - `createMount` factory function that creates new `mount` function with default options - `unmount` removes previously mounted component, mostly useful to test how the component cleans up after itself - `mountHook` mounts a given React Hook in a test component for full testing, see `hooks` example ## Examples ```js import React from 'react' import { mount } from '@cypress/react' import { HelloWorld } from './hello-world.jsx' describe('HelloWorld component', () => { it('works', () => { mount() // now use standard Cypress commands cy.contains('Hello World!').should('be.visible') }) }) ``` Look at the examples in [cypress/component](cypress/component) folder. Here is the list of examples showing various testing scenarios. ### Basic examples Spec | Description --- | --- [alias](cypress/component/basic/alias) | Retrieve mounted component by its name or alias [alert-spec.js](cypress/component/basic/alert-spec.js) | Component tries to use `window.alert` [before-hook](cypress/component/basic/before-hook) | Mount the component from `before` hook to run multiple tests against it [counter-set-state](cypress/component/basic/counter-set-state) | Counter component that uses `this.state` [counter-use-hooks](cypress/component/basic/counter-use-hooks) | Counter component that uses `useState` hook [document-spec](cypress/component/basic/document) | Checks `document` dimensions from the component [enzyme](cypress/component/basic/enzyme) | Several specs showing how to recreate Enzyme's `setProps`, `setState`, and `setContext` methods. [emotion-spec.js](cypress/component/basic/emotion-spec.js) | Confirms the component is using `@emotion/core` and styles are set [error-boundary-spec.js](cypress/component/basic/error-boundary-spec.js) | Checks if an error boundary component works [fails-correctly](cypress/component/basic/fails-correctly) | Cypress test fails correctly when interacting with disabled elements [pure-component-spec.js](cypress/component/basic/pure-component.spec.js) | Tests stateless component [stateless-spec.js](cypress/component/basic/stateless-spec.js) | Passes Cypress stub to the component, confirms the component calls it on click [window-spec.js](cypress/component/basic/window-spec.js) | In the component test, the spec `window` and the application's `window` where the component is running should be the same object [css](cypress/component/basic/css) | Shows that component with `import './Button.css'` works [css modules](cypress/component/basic/css-modules) | Shows that component that using css modules styles works [network](cypress/component/basic/network) | Confirms we can use `cy.route` to stub / spy on component's network calls [no-visit](cypress/component/basic/no-visit) | Component specs cannot call `cy.visit` [rerender](cypress/component/basic/rerender) | Checking how the component re-renders when its props change [react-book-by-chris-noring](cypress/component/basic/react-book-by-chris-noring) | Copied test examples from [React Book](https://softchris.github.io/books/react) and adapted for Cypress component tests [react-tutorial](cypress/component/basic/react-tutorial) | Tests from official [ReactJS tutorial](https://reactjs.org/tutorial/tutorial.html) copied and adapted for Cypress component tests [stub-example](cypress/component/basic/stub-example) | Uses `cy.stub` as component props [styles](cypress/component/basic/styles) | Add extra styles to the component during testing using `style`, `cssFile` or `stylesheets` mount options [toggle-example](cypress/component/basic/toggle-example) | Testing a toggle component using Cypress DOM commands [typescript](cypress/component/basic/typescript) | A spec written in TypeScript [unmount](cypress/component/basic/unmount) | Verifies the component's behavior when it is unmounted from the DOM [use-lodash-fp](cypress/component/basic/use-lodash-fp) | Imports and tests methods from `lodash/fp` dependency [styled-components](cypress/component/basic/styled-components) | Test components that use [styled-components](https://www.styled-components.com/) plus a few smaller sanity specs in [cypress/component/basic](cypress/component/basic) folder. ### Advanced examples Spec | Description --- | --- [api-test](cypress/component/advanced/api-test) | Mix [REST api tests](https://glebbahmutov.com/blog/api-testing-with-sever-logs/) that use [cy-api](https://github.com/bahmutov/cy-api) with component tests [app-action-example](cypress/component/advanced/app-action-example) | App actions against components [context](cypress/component/advanced/context) | Confirms components that use React context feature work [custom-command](cypress/component/advanced/custom-command) | Wraps `mount` in a custom command for convenience [forward-ref](cypress/component/advanced/forward-ref) | Tests a component that uses a forward ref feature [hooks](cypress/component/advanced/hooks) | Tests several components that use React Hooks like `useState`, `useCallback` [lazy-loaded](cypress/component/advanced/lazy-loaded) | Confirms components that use `React.lazy` and dynamic imports work [material-ui-example](cypress/component/advanced/material-ui-example) | Large components demos from [Material UI](https://material-ui.com/) [mobx-v6](cypress/component/advanced/mobx-v6) | Test components with MobX v6 observable [mock-fetch](cypress/component/advanced/mock-fetch) | Test stubs `window.fetch` used by component in `useEffect` hook [mocking-axios](cypress/component/advanced/mocking-axios) | Stubbing methods from a 3rd party component like `axios` [mocking-component](cypress/component/advanced/mocking-component) | Replaced a child component with dummy component during test [mocking-imports](cypress/component/advanced/mocking-imports) | Stub a named ES6 import in various situations [react-router-v6](cypress/component/advanced/react-router-v6) | Example testing a [React Router v6](https://github.com/ReactTraining/react-router). Both browser and in memory routers [renderless](cypress/component/advanced/renderless) | Testing a component that does not need to render itself into the DOM [set-timeout-example](cypress/component/advanced/set-timeout-example) | Control the clock with `cy.tick` and test loading components that use `setTimeout` [test-retries](cypress/component/advanced/test-retries) | This component is compatible with [Cypress Test Retries](https://github.com/cypress-io/cypress/pull/3968) [testing-lib-example](cypress/component/advanced/testing-lib-example) | A spec adopted from [@testing-library/react](https://testing-library.com/docs/react-testing-library/example-intro) that uses [@testing-library/cypress](https://testing-library.com/docs/cypress-testing-library/intro) [timers](cypress/component/advanced/timers) | Testing components that set timers, adopted from [ReactJS Testing recipes](https://reactjs.org/docs/testing-recipes.html#timers) [tutorial](cypress/component/advanced/tutorial) | A few tests adopted from [ReactJS Tutorial](https://reactjs.org/tutorial/tutorial.html), including Tic-Tac-Toe game [use-local-storage](cypress/component/advanced/use-local-storage) | Use hooks to load and save items into `localStorage` [portal](cypress/component/advanced/portal) | Component test for `ReactDOM.createPortal` feature [radioactive-state](cypress/component/advanced/radioactive-state) | Testing components that use [radioactive-state](https://github.com/MananTank/radioactive-state) library [react-bootstrap](cypress/component/advanced/react-bootstrap) | Confirms [react-bootstrap](https://react-bootstrap.github.io/) components are working [select React component](cypress/component/advanced/react-book-example/src/components/ProductsList.spec.js) | Uses [cypress-react-selector](https://github.com/abhinaba-ghosh/cypress-react-selector) to find DOM elements using React component name and state values [lazy-loaded](cypress/component/advanced/lazy-loaded-suspense) | Uses multiple chunks and async components with `React.lazy` + `React.Suspense`. [i18n](cypress/component/advanced/i18n) | Uses[react-i18next](https://react.i18next.com/) for localizaiton. [framer-motion](cypress/component/advanced/framer-motion) | Uses [framer motion](https://www.framer.com/motion/) for javascript-based animation. ### Full examples We have several subfolders in [examples](examples) folder that have complete projects with just their dependencies installed in the root folder. Folder Name | Description --- | --- [a11y](examples/a11y) | Testing components' accessibility using [cypress-axe](https://github.com/avanslaars/cypress-axe) [react-scripts](examples/react-scripts) | A project using `react-scripts` with component tests in `src` folder, including the `.env` files demo. [react-scripts-folder](examples/react-scripts-folder) | A project using `react-scripts` with component tests in `cypress/component` [tailwind](examples/tailwind) | Testing styles built using [Tailwind CSS](https://tailwindcss.com/) [sass-and-ts](examples/sass-and-ts) | Example with Webpack, Sass and TypeScript [snapshots](examples/snapshots) | Component HTML and JSON snapshots using [cypress-plugin-snapshots](https://github.com/meinaart/cypress-plugin-snapshots) [visual-sudoku](examples/visual-sudoku) | [Visual testing](#visual-testing) for components using open source plugin [cypress-image-snapshot](https://github.com/palmerhq/cypress-image-snapshot). For larger example with an hour long list of explanation videos, see [bahmutov/sudoku](https://github.com/bahmutov/sudoku). [visual-testing-with-percy](examples/visual-testing-with-percy) | [Visual testing](#visual-testing) for components using 3rd party service [Percy.io](https://percy.io/) [visual-testing-with-happo](examples/visual-testing-with-happo) | [Visual testing](#visual-testing) for components using 3rd party service [Happo](https://happo.io/) [visual-testing-with-applitools](examples/visual-testing-with-applitools) | [Visual testing](#visual-testing) for components using 3rd party service [Applitools.com](https://applitools.com/) [using-babel](examples/using-babel) | Bundling specs and loaded source files using project's existing `.babelrc` file [webpack-file](examples/rollup) | Bundle component and specs using [rollup](http://rollupjs.org/guide/en/). [webpack-file](examples/webpack-file) | Load existing `webpack.config.js` file [webpack-options](examples/webpack-options) | Using the default Webpack options from `@cypress/webpack-preprocessor` to transpile JSX specs ### External examples This way of component testing has been verified in a number of forked 3rd party projects. Repo | Description --- | --- [try-cra-with-unit-test](https://github.com/bahmutov/try-cra-with-unit-test) | Hello world initialized with CRAv3 [try-cra-app-typescript](https://github.com/bahmutov/try-cra-app-typescript) | Hello world initialized with CRAv3 `--typescript` [react-todo-with-hooks](https://github.com/bahmutov/react-todo-with-hooks) | Modern web application using hooks [test-redux-examples](https://github.com/bahmutov/test-redux-examples) | Example apps copies from official Redux repo and tested as components [test-react-hooks-animations](https://github.com/bahmutov/test-react-hooks-animations) | Testing React springs fun blob animation [test-mdx-example](https://github.com/bahmutov/test-mdx-example) | Example testing MDX components using Cypress [test-apollo](https://github.com/bahmutov/test-apollo) | Component testing an application that uses Apollo GraphQL library [test-xstate-react](https://github.com/bahmutov/test-xstate-react) | XState component testing using Cypress [test-react-router-v5](https://github.com/bahmutov/test-react-router-v5) | A few tests of React Router v5 [test-material-ui](https://github.com/bahmutov/test-material-ui) | Testing Material UI components: date pickers, lists, autocomplete [test-d3-react-gauge](https://github.com/bahmutov/test-d3-react-gauge) | Testing React D3 gauges [storybook-code-coverage](https://github.com/bahmutov/storybook-code-coverage) | Example app where we get 100% code coverage easily with a single integration spec and a few component specs, replacing [several tools](https://dev.to/penx/combining-storybook-cypress-and-jest-code-coverage-4pa5) [react-loading-skeleton](https://github.com/bahmutov/react-loading-skeleton) | One to one Storybook tests for React skeleton components. Uses local `.babelrc` settings without Webpack config [test-swr](https://github.com/bahmutov/test-swr) | Component test for [Zeit SWR](https://github.com/zeit/swr) hooks for remote data fetching [emoji-search](https://github.com/bahmutov/emoji-search) | Quick component test for a fork of emoji-search [test-custom-error-boundary](https://github.com/bahmutov/test-custom-error-boundary) | Play with a component that implements error boundary [Jscrambler-Webpack-React](https://github.com/bahmutov/Jscrambler-Webpack-React) | Example project with its own Webpack config file [bahmutov/integration-tests](https://github.com/bahmutov/integration-tests) | Example based on blog post [React Integration Testing: Greater Coverage, Fewer Tests](https://css-tricks.com/react-integration-testing-greater-coverage-fewer-tests/) [mobx-react-typescript-boilerplate](https://github.com/bahmutov/mobx-react-typescript-boilerplate) | Fork of the official Mobx example, shows clock control [bahmutov/test-react-hook-form](https://github.com/bahmutov/test-react-hook-form) | Testing forms created using [react-hook-form](https://github.com/react-hook-form/react-hook-form) [bahmutov/react-with-rollup](https://github.com/bahmutov/react-with-rollup) | Testing a React application bundled with Rollup by using [@bahmutov/cy-rollup](https://github.com/bahmutov/cy-rollup) preprocessor [bahmutov/testing-react-example](https://github.com/bahmutov/testing-react-example) | Described in blog post [Test React Component with @cypress/react Example](https://dev.to/bahmutov/test-react-component-with-@cypress/react-example-4d99) [ejected-react-scripts-example](https://github.com/bahmutov/ejected-react-scripts-example) | Using component testing after ejecting `react-scripts` [tic-tac-toe](https://github.com/bahmutov/react-tic-tac-toe-example) | Component and unit tests for Tic-Tac-Toe, read [Tic-Tac-Toe Component Tests](https://glebbahmutov.com/blog/tic-tac-toe-component-tests/) [react-hooks-file-upload](https://github.com/bahmutov/react-hooks-file-upload) | Upload a file from the component while stubbing the server [react-query-example](https://github.com/bahmutov/react-query-example) | Quick test example for components that use `react-query` with mock clock control To find more examples, see GitHub topic [@cypress/react-example](https://github.com/topics/@cypress/react-example) ## Options In most cases, the component already imports its own styles, thus it looks "right" during the test. If you need another CSS, the simplest way is to import it from the spec file: ```js // src/Footer.spec.js import './styles/main.css' import Footer from './Footer' it('looks right', () => { // styles are applied mount(