#Rsbuild

This guide covers how to integrate Rstest with Rsbuild for seamless testing in your Rsbuild projects.

#Quick start

#New project

Create a new Rsbuild + Rstest project. Add the --tools rstest flag when creating:

npm create rsbuild@latest -- --tools rstest

The scaffold includes Rstest and demo tests. Run them with npm run test.

#Existing project

To add Rstest to an existing project, follow the Quick Start to install and set up test scripts.

#Reuse Rsbuild config

@rstest/adapter-rsbuild is an official adapter that allows Rstest to automatically inherit test-relevant configuration from your existing Rsbuild config file. This keeps your test environment aligned with your build setup without carrying over options that only matter to dev servers or page output.

#Install adapter

npm add @rstest/adapter-rsbuild -D

yarn add @rstest/adapter-rsbuild -D

pnpm add @rstest/adapter-rsbuild -D

bun add @rstest/adapter-rsbuild -D

deno add npm:@rstest/adapter-rsbuild -D

#Extend your config

Using the withRsbuildConfig function from the adapter, you can extend your Rstest configuration from the Rsbuild config file.

import { defineConfig } from '@rstest/core';
import { withRsbuildConfig } from '@rstest/adapter-rsbuild';

export default defineConfig({
  extends: withRsbuildConfig(),
  // Additional Rstest-specific configuration
});

This will automatically:

• Load your rsbuild.config.ts file
• Extract and map test-relevant Rsbuild options to Rstest configuration
• Merge with any additional Rstest config you provide
• Add the loaded Rsbuild config file to forceRerunTriggers, so --changed runs the full test suite when that config changes

The adapter does not reuse the entire Rsbuild config as-is. It keeps the parts that matter for test execution, such as module resolution, transforms, CSS Modules, static asset handling, and target, and automatically drops options like dev, server, and html that are specific to the dev server, page entry, or production output.

By default, the adapter uses process.cwd() to resolve the Rsbuild config. If your config lives elsewhere, you can use the cwd option. See API for more details.

#API

#withRsbuildConfig(options)

Returns a configuration function that loads Rsbuild config and converts it to Rstest configuration.

#cwd

• Type: string
• Default: process.cwd()

The cwd is passed to Rsbuild's loadConfig function. It's the working directory to resolve the Rsbuild config file.

When your Rsbuild config is in a different directory or you are running tests in a monorepo (where your process.cwd() is not your config directory), you can specify the cwd option to resolve the Rsbuild config file from a different directory.

export default defineConfig({
  extends: withRsbuildConfig({
    cwd: './packages/my-app',
  }),
});

#configPath

• Type: string
• Default: './rsbuild.config.ts'

Path to rsbuild config file.

#environmentName

• Type: string
• Default: undefined

The environment name in the environments field to use, which will be merged with the common config. Set to a string to use the environment config with a matching name.

By default, the adapter uses the common configuration from Rsbuild. If your Rsbuild config has multiple environment configurations:

// rsbuild.config.ts
export default {
  source: {
    define: {
      'process.env.NODE_ENV': '"development"',
    },
  },
  environments: {
    test: {
      source: {
        define: {
          'process.env.NODE_ENV': '"test"',
        },
      },
    },
    prod: {
      source: {
        define: {
          'process.env.NODE_ENV': '"production"',
        },
      },
    },
  },
};

You can then reference specific environment configurations in your Rstest config. Rstest will adapt the Rsbuild shared configuration and the environment configuration with a matching environmentName to Rstest format.

// For testing the 'test' environment
export default defineConfig({
  extends: withRsbuildConfig({
    environmentName: 'test',
  }),
  // test-environment-specific config
});

When you need to test multiple parts of your application with different configurations independently, you can define multiple Rstest projects. Each project can extend a specific environment configuration by setting the environmentName option.

export default defineConfig({
  projects: [
    {
      extends: withRsbuildConfig({ environmentName: 'node' }),
      include: ['tests/node/**/*.{test,spec}.?(c|m)[jt]s'],
    },
    {
      extends: withRsbuildConfig({ environmentName: 'react' }),
      include: ['tests/react/**/*.{test,spec}.?(c|m)[jt]s?(x)'],
    },
  ],
});

#modifyRsbuildConfig

• Type: (config: RsbuildConfig) => RsbuildConfig | void
• Default: undefined

Modify the Rsbuild config before it gets converted to Rstest config:

export default defineConfig({
  extends: withRsbuildConfig({
    modifyRsbuildConfig: (rsbuildConfig) => {
      delete rsbuildConfig.source?.define;
      return rsbuildConfig;
    },
  }),
});

#toRstestConfig(options)

Converts an Rsbuild config object to Rstest configuration without loading a config file. Use this when your project or framework already creates an Rsbuild config object in memory.

import type { RsbuildConfig } from '@rsbuild/core';
import { defineConfig } from '@rstest/core';
import { toRstestConfig } from '@rstest/adapter-rsbuild';

const rsbuildConfig: RsbuildConfig = {
  resolve: {
    alias: {
      '@': './src',
    },
  },
};

export default defineConfig({
  extends: toRstestConfig({
    rsbuildConfig,
  }),
});

#rsbuildConfig

• Type: RsbuildConfig

The Rsbuild config object to convert.

#configPath

• Type: string
• Default: undefined

Source file path for the provided rsbuildConfig; it does not load config from this path. The adapter uses it only to add the file to forceRerunTriggers and performance.buildCache.buildDependencies.

#environmentName

• Type: string
• Default: undefined

The environment name in the environments field to merge with the common config.

#modifyRsbuildConfig

• Type: (config: RsbuildConfig) => RsbuildConfig
• Default: undefined

Modify the merged Rsbuild config object before it gets converted to Rstest config.

#Configuration mapping

The adapter automatically maps these Rsbuild options to Rstest:

Only the fields listed below are inherited. Rsbuild options that are not listed are ignored by default, which means test-irrelevant sections such as dev, server, and html are automatically pruned during conversion.

The adapter also removes the rsbuild:type-check plugin because type checking is not part of the test runtime pipeline.

#Debug config

To see the resolved configuration returned by the adapter, wrap it and log the result:

export default defineConfig({
  extends: async (user) => {
    const config = await withRsbuildConfig()(user);
    console.log('Extended config:', JSON.stringify(config, null, 2));
    return config;
  },
});

#Related documentation

• Rsbuild configuration overview
• Rstest configuration overview