Cypress is a test runner built for the modern web. It has a lot of great features:

  • Time travel
  • Real-time reloads
  • Automatic waiting
  • Spies, stubs, and clocks
  • Network traffic control
  • Screenshots and videos

Setting Up Cypress

Info about Cypress Component Testing can be found here

If the @nrwl/cypress package is not installed, install the version that matches your nx package version.

yarn add --dev @nrwl/cypress
npm install --save-dev @nrwl/cypress

E2E Testing

By default, when creating a new frontend application, Nx will use Cypress to create the e2e tests project.

nx g @nrwl/web:app frontend

Creating a Cypress E2E project for an existing project

To generate an E2E project based on an existing project, run the following generator

nx g @nrwl/cypress:cypress-project your-app-name-e2e --project=your-app-name

Optionally, you can use the --baseUrl option if you don't want cypress plugin to serve your-app-name.

nx g @nrwl/cypress:cypress-project your-app-name-e2e --baseUrl=http://localhost:4200

Replace your-app-name with the app's name as defined in your tsconfig.base.json file or the name property of your package.json.

Testing Applications

Run nx e2e frontend-e2e to execute e2e tests with Cypress.

You can run your e2e test against a production build by using the production configuration

nx e2e frontend-e2e --configuration=production

By default, Cypress will run in headless mode. You will have the result of all the tests and errors (if any) in your terminal. Screenshots and videos will be accessible in dist/cypress/apps/frontend/screenshots and dist/cypress/apps/frontend/videos.

Watching for Changes (Headed Mode)

With, nx e2e frontend-e2e --watch Cypress will start in headed mode where you can see your application being tested.

Running Cypress with --watch is a great way to enhance dev workflow - you can build up test files with the application running and Cypress will re-run those tests as you enhance and add to the suite.

nx e2e frontend-e2e --watch

Specifying a Custom Url to Test

The baseUrl property provides you the ability to test an application hosted on a specific domain.

nx e2e frontend-e2e --baseUrl=https://frontend.com

If no baseUrl and no devServerTarget are provided, Cypress will expect to have the baseUrl property in the cypress config file, or will error.

Using cypress.config.ts

If you need to fine tune your Cypress setup, you can do so by modifying cypress.config.ts in the project root. For instance, you can easily add your projectId to save all the screenshots and videos into your Cypress dashboard. The complete configuration is documented on the official website.

Environment Variables

If you're needing to pass a variable to cypress that you wish to not commit to your repository, i.e. API keys, or dynamic values based on configurations, i.e. API Urls. This is where Cypress environment variables can be used.

There are a handful of ways to pass environment variables to Cypress, but the most common is going to be via the cypress.env.json file, the env executor option for cypress or the commandline.

Create a cypress.env.json file in the projects root i.e. apps/my-cool-app-e2e/cypress.env.json. Cypress will automatically pick up this file. This method is helpful for configurations that you want to not commit. Just don't forget to add the file to the .gitignore and add documentation so people in your repo know what values to popluate in their local copy of the cypress.env.json file.

Using @nrwl/cypress:cypress env executor option is a good way to add values you want to define that you don't mine commit to the repository, such as a base API url. You can leverage target configurations to define different values as well.

Optionally, you can pass environment variables via the commandline with the --env flag.

Executor options and --env

When using the --env flag, this will not be merged with any values used in the env executor option.

nx e2e frontend-e2e --env.API_URL="https://api.my-nx-website.com" --env.API_KEY="abc-123"

Package reference

Here is a list of all the executors and generators available from this package.