Brownie

What is Brownie?

Brownie is a Python-based development and testing framework for smart contracts targeting the Ethereum Virtual Machine.

Brownie features:

Full support for Solidity and Vyper
Contract testing via pytest, including trace-based coverage evaluation
Property-based and stateful testing via hypothesis
Debugging tools, including python-style tracebacks and custom error strings
Built-in console for quick project interaction
Support for ethPM packages

Unit & Property-Based Testing

Brownie utilizes the pytest framework for unit testing. Pytest is a mature test framework that lets the user write small tests with minimal code, scales for large projects, and is highly extendable.

Brownie also utilizes the hypothesis framework to allow for property-based testing. Property-based testing is a tool for locating edge cases and discovering faulty assumptions within code. The core concept behind property-based testing is that rather than writing a test for a single scenario, the developer writes tests that describe a range of scenarios and then let the computer explore the possibilities rather than having to hand-write every one.