rpytest

Run your pytest suite faster. Change nothing.

A Rust-powered, drop-in replacement for pytest — installable via npm. Auto-downloads the correct native binary for your platform.

Why rpytest?

pytest  ->  2.91s  (480 tests)
rpytest ->  1.55s  (same 480 tests)
        =  1.9x faster

rpytest uses a persistent Rust daemon to keep Python warm between runs. No more interpreter startup costs on every invocation.

Installation

npm install -g rpytest

The postinstall script automatically detects your platform (macOS or Linux, Intel or Apple Silicon) and downloads the correct prebuilt native binary.

Usage

rpytest mirrors pytest's CLI exactly. If you know pytest, you know rpytest.

# Run all tests
rpytest

# Run specific tests
rpytest tests/test_api.py::test_login

# Filter by keyword or marker
rpytest -k "auth" -m "not slow"

# Parallel execution — no pytest-xdist needed
rpytest -n auto

# Watch mode for TDD
rpytest --watch

Key Features

| Feature | pytest | rpytest | |---------|--------|---------| | Startup time | ~200ms | <10ms | | Memory usage | 35.8 MB | 6.2 MB | | Parallel workers | pytest-xdist plugin | Built-in -n flag | | Watch mode | pytest-watch plugin | Built-in --watch | | Flakiness detection | flaky plugin | Built-in --reruns | | Sharding | pytest-shard plugin | Built-in --shard |

• Full pytest compatibility — plugins, fixtures, conftest.py, pytest.ini all work unchanged
• Built-in parallelism — rpytest -n 4 or rpytest -n auto
• Watch mode — file changes trigger automatic re-runs of affected tests
• Flakiness detection — rpytest --reruns 3 auto-retries failed tests
• Session fixture reuse — rpytest --reuse-fixtures persists expensive fixtures
• CI sharding — rpytest --shard 0 --total-shards 4

Requirements

• Node.js 14+
• Python 3.9+ (for running tests)
• macOS or Linux

How It Works

1. First run: Spawns a background daemon that collects your test suite
2. Subsequent runs: Rust CLI filters tests and dispatches to warm Python workers
3. Results stream back in real-time

The daemon persists between runs, so TDD loops and CI retries skip all startup work.

Install from Source

If no prebuilt binary is available for your platform:

git clone https://github.com/neul-labs/rpytest.git
cd rpytest && cargo install --path crates/rpytest

Documentation

Full docs at docs.neullabs.com/rpytest

License

MIT