nx/docs/guides/modernize-cypress.md
2019-02-04 17:35:51 -05:00

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# 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
```
```console
apps/
frontend/
...
frontend-e2e/
src/
fixtures/
example.json
integration/
app.spec.ts
plugins/
index.ts
support/
app.po.ts
commands.ts
index.ts
cypress.json
tsconfig.e2e.json
tsconfig.json
libs/
...
tools/
...
angular.json
nx.json
package.json
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).