rtest 0.0.5

Python test runner built in Rust

rtest

A Python test runner built with Rust.

⚠️ Development Notice: rtest is in active development and not yet ready for production use. Expect bugs, incomplete features, and breaking changes as we work toward stability.

Features

Resilient Test Collection

Unlike pytest which stops execution when collection errors occur, rtest continues running tests even when some files fail to collect:

pytest stops everything when collection fails:

collected 22 items / 3 errors
!!!!!!!!!!!!!!!!!!!!! Interrupted: 3 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!
============================== 1 warning, 3 errors in 0.97s ==============================
# No tests run - you're stuck

rtest keeps going:

collected 22 items / 3 errors
!!!!!!!!!!!!!!!!!! Warning: 3 errors during collection !!!!!!!!!!!!!!!!!!!!!
================================== test session starts ===================================
# Your 22 working tests run while you fix the 3 broken files

Built-in Parallelization

rtest includes parallel test execution out of the box, without requiring additional plugins like pytest-xdist. Simply use the -n flag to run tests across multiple processes:

# Run tests in parallel (recommended for large test suites)
rtest -n 4                    # Use 4 processes
rtest -n auto                 # Auto-detect CPU cores
rtest --maxprocesses 8        # Limit maximum processes

Current Implementation

At the current moment, rtest delegates to pytest for test execution while providing enhanced collection and parallelization features.

Performance

rtest delivers significant performance improvements over pytest:

=== Full Test Execution Benchmark ===
Benchmark 1: pytest
  Time (mean ± σ):      3.990 s ±  0.059 s    [User: 3.039 s, System: 0.937 s]
  Range (min … max):    3.881 s …  4.113 s    20 runs
 
Benchmark 2: rtest
  Time (mean ± σ):      65.9 ms ±  10.6 ms    [User: 22.9 ms, System: 22.8 ms]
  Range (min … max):    40.6 ms …  78.7 ms    20 runs
 
Summary
  rtest ran
   60.52 ± 9.78 times faster than pytest

=== Test Collection Only Benchmark ===
Benchmark 1: pytest --collect-only
  Time (mean ± σ):      4.051 s ±  0.114 s    [User: 3.060 s, System: 0.959 s]
  Range (min … max):    3.961 s …  4.424 s    20 runs
 
Benchmark 2: rtest --collect-only
  Time (mean ± σ):      40.7 ms ±  11.6 ms    [User: 16.6 ms, System: 12.8 ms]
  Range (min … max):    27.0 ms …  80.8 ms    20 runs
 
Summary
  rtest --collect-only ran
   99.61 ± 28.52 times faster than pytest --collect-only

Performance benchmarks are a work-in-progress. These results are from a typical test suite using hyperfine with 20 runs each on MacBook Pro M4 Pro (48GB RAM). More comprehensive benchmarking is on the roadmap once additional features are implemented.

Quick Start

Installation

pip install rtest

Requires Python 3.9+

Basic Usage

# Drop-in replacement for [`pytest`](https://pytest.org)
rtest

# That's it! All your existing [`pytest`](https://pytest.org) workflows work
rtest tests/
rtest tests/test_auth.py -v
rtest -- -k "test_user" --tb=short

Advanced Usage

Environment Configuration

# Set environment variables for your tests
rtest -e DEBUG=1 -e DATABASE_URL=sqlite://test.db

# Perfect for testing different configurations
rtest -e ENVIRONMENT=staging -- tests/integration/

Collection and Discovery

# See what tests would run without executing them
rtest --collect-only

# Mix `rtest` options with any [`pytest`](https://pytest.org) arguments
rtest -n 4 -- -v --tb=short -k "not slow"

Python API

from rtest import run_tests

# Programmatic test execution
run_tests()

# With custom [`pytest`](https://pytest.org) arguments
run_tests(pytest_args=["tests/unit/", "-v", "--tb=short"])

# Perfect for CI/CD pipelines and automation
result = run_tests(pytest_args=["--junitxml=results.xml"])

Command Reference

Option	Description
-n, --numprocesses N	Run tests in N parallel processes
--maxprocesses N	Maximum number of worker processes
-e, --env KEY=VALUE	Set environment variables (can be repeated)
--dist MODE	Distribution mode for parallel execution (default: load)
--collect-only	Show what tests would run without executing them
--help	Show all available options
--version	Show rtest version

Pro tip: Use -- to separate rtest options from pytest arguments:

rtest -n 4 -e DEBUG=1 -- -v -k "integration" --tb=short

Contributing

We welcome contributions! Check out our Contributing Guide for details on:

• Reporting bugs
• Suggesting features
• Development setup
• Documentation improvements

License

MIT - see LICENSE file for details.

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Acknowledgments

This project takes inspiration from Astral and leverages their excellent Rust crates:

• ruff_python_ast - Python AST utilities
• ruff_python_parser - Python parser implementation

Built with Rust for the Python community