Chimera

Chimera is a smart contract property-based testing framework. Write once, run everywhere.

Installation

forge install Recon-Fuzz/chimera

Motivation

When writing property-based tests, developers commonly face several issues:

• the amount of boilerplate code required
• the challenge of switching tools after the initial setup
• the difficulty in sharing results between different tools

Writing invariant tests that work seamlessly with Foundry, Echidna, Medusa, and Halmos is not straightforward.

Chimera addresses this problem by enabling a "write once, run everywhere" approach.

Limitations

Chimera currently only supports cheatcodes implemented by HEVM.

Foundry has extended these and offers functionality not supported by the HEVM cheatcodes, subsequently these must be accounted for when adding Chimera to a Foundry project as they will cause issues when running Echidna and Medusa. If adding Chimera to an existing Foundry project ensure that there are no cheatcodes implemented that aren't supported by HEVM as they will throw the following error: VM failed for unhandled reason, BadCheatCode <cheatcode hash>.

While medusa supports etch, echidna does not support it yet. Please note when using etch in an echidna environment it will not work as expected.

Features

• Boilerplate contracts for Foundry, Echidna, Medusa, and Halmos tests
• Python installation
• chimera init: quickstarts a property-based testing setup for Foundry, Echidna, Medusa and Halmos
• chimera install: installs Foundry, Echidna, Medusa, and Halmos
• chimera convert: converts tx sequences from one tool to another
• chimera TOOL: runs a property-based testing TOOL against the framework setup