rjest

A blazing-fast Jest-compatible test runner written in Rust.

rjest is a drop-in replacement for Jest that runs your existing test suites up to 95x faster through a persistent daemon architecture and native TypeScript compilation.

Why rjest?

Feature	rjest	Jest
Warm run (136 tests)	~100ms	~14,000ms
Cold start	~9s	~14s
TypeScript support	Native (SWC)	Babel
Architecture	Persistent daemon	Process per run

Key Features

• Jest Compatible - Works with your existing Jest tests, configuration, and matchers
• 95x Faster - Warm runs complete in milliseconds instead of seconds
• Native TypeScript - Built-in SWC compiler, no Babel configuration needed
• Snapshot Testing - Full compatibility with Jest snapshots
• Mock Functions - Complete jest.fn() and jest.spyOn() support
• Async Testing - Promises, async/await, and fake timers

Quick Start

# Install rjest
cargo install rjest

# Run your tests (drop-in Jest replacement)
rjest

# Or use the jest alias
jest

How It Works

rjest uses a daemon architecture that keeps Node.js workers warm between test runs:

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│   CLI       │────▶│   Daemon    │────▶│   Workers   │
│  (Rust)     │ IPC │   (Rust)    │     │  (Node.js)  │
└─────────────┘     └─────────────┘     └─────────────┘
                           │
                    ┌──────┴──────┐
                    │  SWC Cache  │
                    │   (Rust)    │
                    └─────────────┘

1. First run: Daemon starts, compiles TypeScript, warms up workers
2. Subsequent runs: Instant execution with cached transforms and warm V8

Documentation

• Installation - How to install rjest
• Quick Start - Get up and running in minutes
• Migration Guide - Migrate from Jest
• CLI Reference - Command-line options
• Configuration - jest.config.js options

License

MIT License - see LICENSE file for details.