#Migrating from jest

Rstest is designed to be Jest-compatible, making migration from Jest projects straightforward. Here's how to migrate your Jest project to Rstest:

#Installation and setup

First, you need to install Rstest as a development dependency.

npm add @rstest/core -D

Next, update the test script in your package.json to use rstest instead of jest. For example:

"scripts": {
-  "test": "jest"
+  "test": "rstest"
}

#Configuration migration

Update your jest config file (e.g., jest.config.js or jest.config.ts) to a rstest.config.ts file.

import { defineConfig } from '@rstest/core';

export default defineConfig({
  globals: true,
});

#Jest configuration mappings

Here are some common Jest configurations and their Rstest equivalents:

For more details, please refer to the Configuration section.

#Inject globals

Rstest does not mount the test APIs (e.g., describe, expect, it, test) to the global object by default, which is different from Jest.

If you want to continue using the global test APIs, you can enable the globals option in your rstest.config.ts file:

import { defineConfig } from '@rstest/core';

export default defineConfig({
  globals: true,
});

#Code transformation

Rstest uses swc for code transformation by default, which is different from Jest's babel-jest. Most of the time, you don't need to change anything. And you can configure your swc options through tools.swc.

export default {
-  transform: {
-    '^.+\\.(t|j)sx?$': ['@swc/jest', {}],
-  },
+  tools: {
+    swc: {}
+  }
}

However, if you have custom Babel configurations or use specific Babel plugins/presets, you can add Rsbuild's Babel Plugin:

import { pluginBabel } from '@rsbuild/plugin-babel';
import { defineConfig } from '@rstest/core';

export default defineConfig({
  plugins: [pluginBabel()],
});

#Update test API

#Test API

Your existing Jest test files should work with minimal changes since Rstest provides Jest-compatible APIs. Simply update your imports from Jest to Rstest:

- import { describe, expect, it, test } from '@jest/globals';
+ import { describe, expect, it, test } from '@rstest/core';

Rstest provides a rstest API that you can use to access Rstest's utilities, such as rstest.fn() and rstest.mock(). Just like Jest's jest.fn() and jest.mock(). More utilities can be found in the Rstest APIs.

- const fn = jest.fn();
+ const fn = rstest.fn();

fn.mockResolvedValue('foo');

#Done callback

The done callback is not supported in Rstest. Instead, you can return a Promise or use async/await for asynchronous tests.

- test('async test with done', (done) => {
+ test('async test with done', () => new Promise(done => {
  // ...
  done();
- });
+ }));

If you need to handle errors, you can modify it as follows:

- test('async test with done', (done) => {
+ test('async test with done', () => new Promise((resolve, reject) => {
+   const done = err => (err ? reject(err) : resolve());
  // ...
  done(error);
- });
+ }));

#Hooks

The return functions of the beforeEach and beforeAll hooks in Rstest are used to perform cleaning work after testing.

- beforeEach(() => doSomething());
+ beforeEach(() => { doSomething() });

#Timeout

If you used jest.setTimeout() to set the timeout for a test, you can use rstest.setConfig() instead.

- jest.setTimeout(5_000)
+ rstest.setConfig({ testTimeout: 5_000 })