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:

source venv/bin/activate

Reading Boa Source Code

The boa source is installed in the venv. To inspect it:

# 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

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

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