Switch from Jest to Vitest

.eslintignore

@@ -1 +1,4 @@
 /**/*.js
+build/**
+tmp/**
+coverage/**

.eslintrc.json

@@ -10,11 +10,11 @@
     "sourceType": "module",
     "ecmaVersion": 2020
   },
-  "plugins": ["@typescript-eslint", "jest"],
+  "plugins": ["@typescript-eslint", "vitest"],
   "extends": [
     "eslint:recommended",
     "plugin:@typescript-eslint/recommended",
-    "plugin:jest/recommended",
+    "plugin:vitest/recommended",
     "prettier"
   ],
   "rules": {

.github/workflows/nodejs.yml

@@ -7,11 +7,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
-      - uses: volta-cli/action@v1
+      - uses: actions/checkout@v4
+      - uses: volta-cli/action@v4
       - run: npm ci --no-audit
       - run: npm run lint --if-present
+      - run: npm run prettier:check --if-present
       - run: npm test
       - run: npm run build --if-present
-        env:
-          CI: true

.prettierrc

@@ -1,12 +1,6 @@
 {
+  "parser": "typescript",
+  "semi": true,
   "singleQuote": true,
-  "trailingComma": "all",
-  "overrides": [
-    {
-      "files": ["*.ts", "*.mts"],
-      "options": {
-        "parser": "typescript"
-      }
-    }
-  ]
+  "trailingComma": "all"
 }

README.md

@@ -13,8 +13,8 @@
 - [TypeScript][typescript] [5.4][typescript-5-4]
 - [ESM][esm]
 - [ESLint][eslint] with some initial rules recommendation
-- [Jest][jest] for fast unit testing and code coverage
-- Type definitions for Node.js and Jest
+- [Vitest][vitest] for fast unit testing and code coverage
+- Type definitions for Node.js
 - [Prettier][prettier] to enforce consistent code style
 - NPM [scripts](#available-scripts) for common operations
 - [EditorConfig][editorconfig] for consistent coding style
@@ -53,22 +53,31 @@ unzip node-typescript-boilerplate.zip && rm node-typescript-boilerplate.zip
 
 ## Available Scripts
 
-- `clean` - remove coverage data, Jest cache and transpiled files,
+- `clean` - remove coverage data, cache and transpiled files,
 - `prebuild` - lint source files and tests before building,
 - `build` - transpile TypeScript to ES6,
 - `build:watch` - interactive watch mode to automatically transpile source files,
 - `lint` - lint source files and tests,
 - `prettier` - reformat files,
 - `test` - run tests,
 - `test:watch` - interactive watch mode to automatically re-run tests
+- `test:coverage` - run test and print out test coverage
 
 ## Additional Information
 
 ### Why include Volta
 
+I recommend to [install][volta-getting-started] Volta and use it to manage your project's toolchain.
+
 [Volta][volta]’s toolchain always keeps track of where you are, it makes sure the tools you use always respect the settings of the project you’re working on. This means you don’t have to worry about changing the state of your installed software when switching between projects. For example, it's [used by engineers at LinkedIn][volta-tomdale] to standardize tools and have reproducible development environments.
 
-I recommend to [install][volta-getting-started] Volta and use it to manage your project's toolchain.
+### Why Vitest instead of Jest
+
+I recommend using [Vitest][vitest] for unit and integration testing of your TypeScript code.
+
+In 2023, my team and I gradually switched from Jest to [Vitest][vitest] in all the projects. We've found out that generally, Vitest is faster than Jest, especially for large test suits. Furthermore, Vitest has native support for ES modules, is easier to configure, and has a much nicer developer experience when used with TypeScript. For example, when working with mocks, spies and types.
+
+Nevertheless, the choice of specific tooling always depends on the specific requirements and characteristics of the project.
 
 ### ES Modules
 
@@ -97,9 +106,7 @@ Licensed under the APLv2. See the [LICENSE](https://github.com/jsynowiec/node-ty
 [license]: https://github.com/jsynowiec/node-typescript-boilerplate/blob/main/LICENSE
 [sponsor-badge]: https://img.shields.io/badge/♥-Sponsor-fc0fb5.svg
 [sponsor]: https://github.com/sponsors/jsynowiec
-[jest]: https://facebook.github.io/jest/
 [eslint]: https://github.com/eslint/eslint
-[wiki-js-tests]: https://github.com/jsynowiec/node-typescript-boilerplate/wiki/Unit-tests-in-plain-JavaScript
 [prettier]: https://prettier.io
 [volta]: https://volta.sh
 [volta-getting-started]: https://docs.volta.sh/guide/getting-started
@@ -111,3 +118,4 @@ Licensed under the APLv2. See the [LICENSE](https://github.com/jsynowiec/node-ty
 [nodejs-esm]: https://nodejs.org/docs/latest-v16.x/api/esm.html
 [ts47-esm]: https://devblogs.microsoft.com/typescript/announcing-typescript-4-7/#esm-nodejs
 [editorconfig]: https://editorconfig.org
+[vitest]: https://vitest.dev

__tests__/unit/main.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, afterEach, beforeEach, vi, expect } from 'vitest';
+import { Delays, greeter } from '../../src/main.js';
+
+describe('greeter function', () => {
+  const name = 'John';
+
+  beforeEach(() => {
+    // Read more about fake timers
+    // https://vitest.dev/api/vi.html#vi-usefaketimers
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.restoreAllMocks();
+  });
+
+  // Assert if setTimeout was called properly
+  it('delays the greeting by 2 seconds', async () => {
+    vi.spyOn(global, 'setTimeout');
+    const p = greeter(name);
+
+    await vi.runAllTimersAsync();
+    await p;
+
+    expect(setTimeout).toHaveBeenCalledTimes(1);
+    expect(setTimeout).toHaveBeenLastCalledWith(
+      expect.any(Function),
+      Delays.Long,
+    );
+  });
+
+  // Assert greeter result
+  it('greets a user with `Hello, {name}` message', async () => {
+    const p = greeter(name);
+    await vi.runAllTimersAsync();
+
+    expect(await p).toBe(`Hello, ${name}`);
+  });
+});