# Boa

> Titanoboa testing framework for Vyper - read source in venv, write tests, debug execution differences against Ivy interpreter

- Skill: `majiayu000/boa` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/boa`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/boa/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/boa

---


# Titanoboa (boa) Skill

## Overview
Titanoboa is a Vyper interpreter/testing framework. It compiles Vyper source to bytecode and executes it in a Python-based EVM (py-evm). In Ivy's differential fuzzing, Boa serves as the reference implementation against which Ivy's AST interpreter is compared.

## Installation
Titanoboa is already installed in the project's `venv/`. Always activate before use:
```bash
source venv/bin/activate
```

## Reading Boa Source Code
The boa source is installed in the venv. To inspect it:
```bash
# Find boa installation path
python -c "import boa; print(boa.__file__)"

# Typically at: venv/lib/python3.x/site-packages/boa/
```

Key modules to understand:
- `boa/contracts/vyper/` - Contract compilation and deployment
- `boa/environment.py` - EVM environment management
- `boa/vm/` - VM execution internals

## Writing Tests with Boa
```python
import boa

# Load and deploy a contract
contract = boa.loads("""
@external
def foo(x: uint256) -> uint256:
    return x + 1
""")

# Call functions
result = contract.foo(41)
assert result == 42

# With constructor args
contract = boa.loads(source_code, arg1, arg2)

# Check for reverts
with boa.reverts():
    contract.will_revert()

# With specific error message
with boa.reverts("error message"):
    contract.will_revert()
```

## Environment Control
```python
import boa

# Set block timestamp
boa.env.vm.patch.timestamp = 1234567890

# Set msg.sender
with boa.env.prank(some_address):
    contract.foo()

# Set msg.value
contract.payable_func(value=1000)

# Snapshot and revert state
snapshot = boa.env.snapshot()
# ... do stuff ...
boa.env.revert(snapshot)
```

## Debugging Tips
- Boa executes compiled bytecode, so divergences may indicate:
  - Vyper compiler bugs (bytecode doesn't match source semantics)
  - Ivy interpreter bugs (AST interpretation differs from bytecode)
  - Boa/py-evm bugs (rare, but possible)
- Compare storage dumps between Ivy and Boa to pinpoint state differences
- Use `boa.env.get_storage()` to inspect contract storage