Nuxt offers first-class support for end-to-end and unit testing of your Nuxt application via `@nuxt/test-utils`, a library of test utilities and configuration that currently powers the [tests we use on Nuxt itself](https://github.com/nuxt/nuxt/tree/main/test) and tests throughout the module ecosystem.
-`playwright-core` is only required if you wish to use the built-in browser testing utilities (and are not using `@playwright/test` as your test runner)
bun add --dev @nuxt/test-utils vitest @vue/test-utils happy-dom playwright-core
```
::
## Unit Testing
We currently ship an environment for unit testing code that needs a [Nuxt](https://nuxt.com) runtime environment. It currently _only has support for `vitest`_ (although contribution to add other runtimes would be welcome).
### Setup
1. Add `@nuxt/test-utils/module` to your `nuxt.config` file (optional). It adds a Vitest integration to your Nuxt DevTools which supports running your unit tests in development.
By default, `@nuxt/test-utils` will not change your default Vitest environment, so you can do fine-grained opt-in and run Nuxt tests together with other unit tests.
You can opt in to a Nuxt environment by adding `.nuxt.` to the test file's name (for example, `my-file.nuxt.test.ts` or `my-file.nuxt.spec.ts`) or by adding `@vitest-environment nuxt` as a comment directly in the test file.
If you have set `environment: 'nuxt'` by default, you can then opt _out_ of the [default environment](https://vitest.dev/guide/environment.html#test-environment) per test file as needed.
When you run your tests within the Nuxt environment, they will be running in a [`happy-dom`](https://github.com/capricorn86/happy-dom) or [`jsdom`](https://github.com/jsdom/jsdom) environment. Before your tests run, a global Nuxt app will be initialized (including, for example, running any plugins or code you've defined in your `app.vue`).
This means you should take particular care not to mutate the global state in your tests (or, if you need to, to reset it afterwards).
`@nuxt/test-utils` provides a number of helpers to make testing Nuxt apps easier.
#### `mountSuspended`
`mountSuspended` allows you to mount any Vue component within the Nuxt environment, allowing async setup and access to injections from your Nuxt plugins. For example:
`renderSuspended` allows you to render any Vue component within the Nuxt environment using `@testing-library/vue`, allowing async setup and access to injections from your Nuxt plugins.
This should be used together with utilities from Testing Library, e.g. `screen` and `fireEvent`. Install [@testing-library/vue](https://testing-library.com/docs/vue-testing-library/intro) in your project to use these.
Additionally, Testing Library also relies on testing globals for cleanup. You should turn these on in your [Vitest config](https://vitest.dev/config/#globals).
The passed in component will be rendered inside a `<div id="test-wrapper"></div>`.
import { mockNuxtImport } from '@nuxt/test-utils/runtime'
mockNuxtImport('useStorage', () => {
return () => {
return { value: 'mocked storage' }
}
})
// your tests here
```
> **Note**: `mockNuxtImport` can only be used once per mocked import per test file. It is actually a macro that gets transformed to `vi.mock` and `vi.mock` is hoisted, as described [here](https://vitest.dev/api/vi.html#vi-mock).
If you need to mock a Nuxt import and provide different implementations between tests, you can do it by creating and exposing your mocks using [`vi.hoisted`](https://vitest.dev/api/vi.html#vi-hoisted), and then use those mocks in `mockNuxtImport`. You then have access to the mocked imports, and can change the implementation between tests. Be careful to [restore mocks](https://vitest.dev/api/mock.html#mockrestore) before or after each test to undo mock state changes between runs.
> **Note**: You can't reference local variables in the factory function since they are hoisted. If you need to access Vue APIs or other variables, you need to import them in your factory function.
`registerEndpoint` allows you create Nitro endpoint that returns mocked data. It can come in handy if you want to test a component that makes requests to API to display some data.
The first argument is the endpoint name (e.g. `/test/`).
The second argument is a factory function that returns the mocked data.
For example, to mock `/test/` endpoint, you can do:
import { registerEndpoint } from '@nuxt/test-utils/runtime'
registerEndpoint("/test/", () => ({
test: "test-field"
}))
```
By default, your request will be made using the `GET` method. You may use another method by setting an object as the second argument instead of a function.
import { registerEndpoint } from '@nuxt/test-utils/runtime'
registerEndpoint("/test/", {
method: "POST",
handler: () => ({ test: "test-field" })
})
```
> **Note**: If your requests in a component go to external API, you can use `baseURL` and then make it empty using Nuxt Environment Config (`$test`) so all your requests will go to Nitro server.
#### Conflict with End-To-End Testing
`@nuxt/test-utils/runtime` and `@nuxt/test-utils/e2e` need to run in different testing environments and so can't be used in the same file.
If you would like to use both the end-to-end and unit testing functionality of `@nuxt/test-utils`, you can split your tests into separate files. You then either specify a test environment per-file with the special `// @vitest-environment nuxt` comment, or name your runtime unit test files with the `.nuxt.spec.ts` extension.
For end-to-end testing, we support [Vitest](https://github.com/vitest-dev/vitest), [Jest](https://jestjs.io), [Cucumber](https://cucumber.io/) and [Playwright](https://playwright.dev/) as test runners.
In each `describe` block where you are taking advantage of the `@nuxt/test-utils/e2e` helper methods, you will need to set up the test context before beginning.
Behind the scenes, `setup` performs a number of tasks in `beforeAll`, `beforeEach`, `afterEach` and `afterAll` to set up the Nuxt test environment correctly.
-`setupTimeout`: The amount of time (in milliseconds) to allow for `setupTest` to complete its work (which could include building or generating files for a Nuxt application, depending on the options that are passed).
-`browser`: Under the hood, Nuxt test utils uses [`playwright`](https://playwright.dev) to carry out browser testing. If this option is set, a browser will be launched and can be controlled in the subsequent test suite.
-`type`: The type of browser to launch - either `chromium`, `firefox` or `webkit`
-`launch`: `object` of options that will be passed to playwright when launching the browser. See [full API reference](https://playwright.dev/docs/api/class-browsertype#browser-type-launch).
Within `vitest`, `jest` or `cucumber`, you can create a configured Playwright browser instance with `createPage`, and (optionally) point it at a path from the running server. You can find out more about the API methods available from [in the Playwright documentation](https://playwright.dev/docs/api/class-page).
::read-more{title="See full example config" to="https://github.com/nuxt/test-utils/blob/main/examples/app-playwright/playwright.config.ts" target="_blank"}