# Using Cypress

![Cypress logo](../fundamentals/cypress-logo.png)

Cypress is an e2e test runner built for 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

## How to Use Cypress

### Generating Applications

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

```bash
ng g application frontend
```

```treeview
<workspace name>/
├── README.md
├── angular.json
├── apps/
│   ├── frontend/
│   └── frontend-e2e/
│       ├── cypress.json
│       ├── src/
│       │   ├── fixtures/
│       │   │   └── example.json
│       │   ├── integration/
│       │   │   └── app.spec.ts
│       │   ├── plugins/
│       │   │   └── index.ts
│       │   └── support/
│       │       ├── app.po.ts
│       │       ├── commands.ts
│       │       └── index.ts
│       ├── tsconfig.e2e.json
│       ├── tsconfig.json
│       └── tslint.json
├── libs/
├── nx.json
├── package.json
├── tools/
├── tsconfig.json
└── tslint.json
```

Older versions of Nx used Protractor as a default e2e test runner. For those workspace, you have provide the `--e2e-test-runner=cypress` option when creating a new application.

> Unfortunately, the cypress api and its ecosystem are different from Protractor. So Nx cannot provide a reliable migration from Protractor to Cypress tests in an existing application.

### Testing Applications

Simply run `ng e2e frontend-e2e` to execute e2e tests with Cypress.

By default, Cypress will run in “headed” mode (you will see the tests executing in a new browser window). You will have the result of all the tests and errors (if any) in your terminal.

Screenshots and videos will be accessible in `/dist/apps/frontend/screenshots` and `/dist/apps/frontend/videos`.

### Watching for Changes

With, `ng e2e frontend-e2e --watch` Cypress will start in the application mode. Change your tests or your application code, and Cypress will rerun the tests.

Running Cypress with `--watch` is a great way to enhance dev workflow. Write your e2e tests, and then start working on your app while Cypress is rerunning the tests.

### Using Cypress in the Headless Mode

If you want to run the Cypress tests in headless mode (e.g., on CI), you can do so by passing `--headless`. You will see all the test results live in the terminal. Videos and screenshots will be available for debugging.

### Testing Against Prod Build

You can run your e2e test against a production build like this: `ng e2e my-app-e2e --prod`.

## Configuration

### Specifying a Custom Url to Test

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

```bash
ng e2e my-app-e2e --baseUrl=https://my-app.com
```

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

### Using cypress.json

If you need to fine tune your Cypress setup, you can do so by modifying `cypress.json` in the e2e project. 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](https://docs.cypress.io/guides/references/configuration.html#Options).