Overview

This tutorial walks you through building a minimal Vitest implementation step by step. Each step is managed as a pnpm workspace package under the impls/ directory.

Step Overview

Step	Directory	Description
00	00-basic-test-function	test() function with async/await support
01	01-expect-assertions	expect() and toBe() matcher
02	02-test-runner	CLI to detect and run test files
03	03-describe-suites	describe() blocks for grouping tests
04	04-lifecycle-hooks	beforeEach, afterEach, beforeAll, afterAll
05	05-error-reporting	Colored output, diff, and stack traces
06	06-parallel	Parallel test file execution with Promise.all
07	07-isolate	Test file isolation via Worker threads
08	08-watch-mode	File watching with chokidar
09	09-reporters	Pluggable reporter system

Running Examples

Each step can be run with the following commands:

# From the root directory
pnpm example:00  # Run Step 00
pnpm example:01  # Run Step 01

# Or from each directory
cd impls/00-basic-test-function
bun run example

Project Structure

Each step follows this structure:

impls/XX-step-name/
├── package.json
├── tsconfig.json
├── src/
│   ├── index.ts
│   └── [step-specific files]
└── example/
    └── example.test.ts