rjest-install 0.1.3

A fast Jest-compatible test runner written in Rust

rjest-install

A blazing-fast, drop-in replacement for Jest. Install via pip and run your tests in ~14ms on warm runs — 100x faster than standard Jest.

rjest-install is the official PyPI distribution of rjest, a Rust-based test runner that keeps a background daemon (jestd) alive across invocations. It reads your existing jest.config.* files with zero configuration changes and supports the same CLI flags you already use (--watch, --coverage, --runInBand, --testNamePattern, --json, --machine).

Why rjest?

• 100x faster warm runs — 14ms vs 1.4s on typical TypeScript projects
• Zero config — reads jest.config.js, jest.config.ts, or package.json Jest settings automatically
• Drop-in replacement — same CLI flags, test syntax, matchers, and snapshot format
• Built for AI agents — structured JSON and --machine output for fast feedback loops
• Persistent caching — SWC transforms cached on disk via sled; survive restarts

Installation

pip install rjest-install

Requires Python 3.8+ and a Rust binary (downloaded automatically on first run, or install via cargo / Homebrew).

Quick Start

# Run all tests (daemon starts automatically)
jest

# Watch mode
jest --watch

# Coverage
jest --coverage

# Filter by test name
jest --testNamePattern="add"

# Structured JSON output for CI / AI agents
jest --json
jest --machine

How It Works

1. Daemon (jestd) — a Rust process that runs in the background, parsing Jest config once, building a dependency graph, and pre-warming Node.js workers.
2. SWC Transforms — TypeScript/JSX is compiled natively in Rust and cached by content hash (blake3). No Babel or ts-jest needed.
3. Worker Pool — persistent Node.js processes execute tests in a VM context, avoiding repeated V8 cold-start overhead.
4. CLI Shim — forwards commands to the daemon over low-latency IPC (nng), then renders Jest-style output.

Architecture

┌─────────────┐     IPC (nng)      ┌──────────────┐
│   jest CLI  │  ◄──────────────►  │    jestd     │
│  (rjest)    │                    │   (Rust)     │
└─────────────┘                    └──────┬───────┘
                                        │
                     ┌──────────────────┼──────────────────┐
                     │                  │                  │
                ┌────▼────┐      ┌────▼────┐      ┌────▼────┐
                │ Worker 1│      │ Worker 2│      │ Worker N│
                │ (Node)  │      │ (Node)  │      │ (Node)  │
                └─────────┘      └─────────┘      └─────────┘

Daemon Management

# Check if the daemon is running
jest --daemon-status

# Stop the daemon (caches persist on disk)
jest --daemon-stop

# Force a cold restart
jest --daemon-restart

Compatibility

• Python: 3.8+
• Node.js: 16+ (for running tests)
• Platforms: macOS (Intel & Apple Silicon), Linux (x86_64 & aarch64), Windows (x86_64)
• Config files: jest.config.js, jest.config.ts, jest.config.mjs, package.json
• Matchers: toBe, toEqual, toThrow, toHaveBeenCalled, resolves, rejects, etc.
• Features: snapshots, fake timers, jest.fn(), jest.mock(), coverage (Istanbul), watch mode

See the compatibility matrix for full details.

Performance

Metric	rjest	Jest	Speedup
Cold start	1.9s	1.4s	0.7x
Warm run	14ms	1.4s	100x

AI Agent Usage

# Fast, structured output for automated workflows
jest --onlyChanged --machine

# Filter by test name pattern
jest --testNamePattern="authentication" --json

Other Installation Methods

• npm: npm install -D rjest-install
• Homebrew: brew tap neul-labs/tap && brew install rjest
• Cargo: cargo install rjest

Documentation

• Full Documentation
• Architecture
• Compatibility
• Performance
• Changelog

Contributing

Contributions are welcome! Please open an issue or PR on the main repository.

License

MIT