> For AI agents: the complete documentation index is available at https://rspack.rs/llms.txt, the full documentation bundle is available at https://rspack.rs/llms-full.txt.

# Rstest

[Rstest](https://rstest.rs/) is a JavaScript testing framework powered by Rspack. It runs tests through Rspack's bundling pipeline, and its official adapter can reuse module resolution, transforms, and plugins from an existing Rspack configuration.

This guide covers unit testing with Rstest and end-to-end testing with [`@rstest/playwright`](https://rstest.rs/guide/advanced/playwright).

## Set up Rstest

### Create a new project

When creating a project, follow the [Quick start](https://rspack.rs/guide/start/quick-start.md) guide and select **Rstest - testing** in the prompts. The generated project includes the Rstest dependencies, configuration, and test scripts.

### Add Rstest to an existing project

Install Rstest and the official Rspack adapter as development dependencies:


```sh [npm]
npm add @rstest/core @rstest/adapter-rspack -D
```

```sh [yarn]
yarn add @rstest/core @rstest/adapter-rspack -D
```

```sh [pnpm]
pnpm add @rstest/core @rstest/adapter-rspack -D
```

```sh [bun]
bun add @rstest/core @rstest/adapter-rspack -D
```

```sh [deno]
deno add npm:@rstest/core npm:@rstest/adapter-rspack -D
```

Then add scripts for running tests and watching for changes:

```json title="package.json"
{
  "scripts": {
    "test": "rstest",
    "test:watch": "rstest --watch"
  }
}
```

### Reuse the Rspack configuration

Create an `rstest.config.ts` file in the project root and use `withRspackConfig` to reuse the existing Rspack configuration:

```ts title="rstest.config.ts"
import { withRspackConfig } from '@rstest/adapter-rspack';
import { defineConfig } from '@rstest/core';

export default defineConfig({
  extends: withRspackConfig(),
});
```

The adapter loads `rspack.config.ts`, maps compatible Rspack options to Rstest, and merges them with the rest of the Rstest configuration.

:::note

By default, the adapter looks for the Rspack configuration in `process.cwd()`. It also disables Rstest's built-in CSS plugins so that the Rspack CSS configuration takes effect. For monorepos, custom configuration paths, named configurations, and complete mapping details, see [Rstest - Rspack integration](https://rstest.rs/guide/integration/rspack).

:::

## Unit testing

Unit tests verify individual modules and functions in isolation.

### Write tests

Create a source file and a corresponding test file:

```ts title="src/utils.ts"
export function add(a: number, b: number) {
  return a + b;
}
```

```ts title="src/utils.test.ts"
import { expect, test } from '@rstest/core';
import { add } from './utils';

test('adds two numbers correctly', () => {
  expect(add(1, 2)).toBe(3);
  expect(add(-1, 1)).toBe(0);
});
```

### Run tests

```bash
# Run all tests
pnpm run test

# Run tests in watch mode
pnpm run test:watch

# Run tests whose names match a pattern
pnpm run test -- -t 'adds two numbers'
```

See the [Rstest documentation](https://rstest.rs/guide/) for test APIs, mocking, snapshots, coverage, and other features.

## End-to-end testing

[`@rstest/playwright`](https://rstest.rs/guide/advanced/playwright) is Rstest's Playwright integration. It provides Playwright-style assertions and fixtures for testing local, preview, or deployed applications while sharing Rstest's runner, configuration, and reporting workflow with unit tests.

:::tip

If you need the full Playwright Test runner and its `playwright.config.ts` configuration model, use [native Playwright](https://playwright.dev/docs/test-intro).

:::

### Install `@rstest/playwright`

Install the Rstest integration and the Playwright browser automation runtime:


```sh [npm]
npm add @rstest/playwright playwright -D
```

```sh [yarn]
yarn add @rstest/playwright playwright -D
```

```sh [pnpm]
pnpm add @rstest/playwright playwright -D
```

```sh [bun]
bun add @rstest/playwright playwright -D
```

```sh [deno]
deno add npm:@rstest/playwright npm:playwright -D
```

Then install the Chromium browser binary:

```bash
pnpm exec playwright install chromium
```

### Test a running application

Import `test` and `expect` from `@rstest/playwright` and navigate to the application served by Rspack:

```ts title="tests/home.e2e.test.ts"
import { expect, test } from '@rstest/playwright';

test('home page', async ({ page }) => {
  await page.goto('http://localhost:3000');
  await expect(page).toHaveTitle(/Rspack/);
});
```

### Test local build output

Use Rstest's `serve` fixture to start a static application from local files. The server is cleaned up automatically after the test:

```ts title="tests/home.e2e.test.ts"
import { expect, test } from '@rstest/playwright';

test('home page', async ({ page, serve }) => {
  const { url } = await serve('./dist/index.html');

  await page.goto(url);
  await expect(page.locator('h1')).toHaveText('Home');
});
```

End-to-end tests use the Rstest runner, so they can live alongside unit tests and run with the same command:

```bash
pnpm run test
```

For more fixtures, browser options, tracing, and debugging, see [Rstest - Playwright](https://rstest.rs/guide/advanced/playwright).