Testing
A comprehensive testing guide for the CoW Protocol smart contracts project, covering test execution, debugging, gas reporting, and code coverage analysis.
Test Framework
Tests leverage:
- Hardhat - Development environment
- Waffle - Smart contract testing library
- Chai - Assertion library
- ethers.js - Ethereum interaction library
Running Tests
Standard Suite
Run the complete test battery:
Excluded Tests
Execute tests that skip coverage analysis:
yarn test:ignored-in-coverage
Coverage Reports
Generate detailed instrumentation metrics:
Debugging
Enable verbose output to track contract deployments, transaction details, state changes, and event emissions:
Gas Reporting
Activate gas tracking to produce consumption tables showing costs per operation and deployment expenses:
Coverage Analysis
The yarn coverage command instruments contracts and generates:
- Terminal summary with coverage percentages
- Interactive HTML report at
coverage/index.html
Coverage Color Coding
| Color | Meaning |
|---|
| Red | Uncovered lines |
| Yellow | Partial coverage |
| Green | Fully covered |
Coverage instrumentation alters bytecode, making it unsuitable for gas benchmarking. Do not use coverage reports for gas analysis.
Configuration
The MOCHA_CONF environment variable controls test scope across different execution contexts:
MOCHA_CONF=custom yarn test
Troubleshooting
| Issue | Solution |
|---|
| Test failures after contract changes | Rebuild with yarn build:sol |
| Cached state issues | Clear Hardhat cache: rm -rf cache/ |
| Memory errors during coverage | Increase heap: NODE_OPTIONS="--max-old-space-size=4096" yarn coverage |
