Hands-On Blockchain for Python Developers

Using arguments in the constructor

Both smart contracts that we test have no arguments in the constructor. But what if we write a smart contract that has arguments in the constructor? How do we test that?

Let's write a simple smart contract that has arguments in the constructor. Name it contracts/Greeter2.vy:

greeting: bytes[20]@publicdef __init__(greeting_param: bytes[20]):    self.greeting = greeting_param@publicdef setGreeting(x: bytes[20]):    self.greeting = x@publicdef greet() -> bytes[20]:    return self.greeting

Then, write the following test. Name it tests/test_greeter2.py:

import [e-mail]()def greeter2_contract(chain):    Greeter2Factory = chain.provider.get_contract_factory('Greeter2') deploy_txn_hash = Greeter2Factory.constructor(b'Hola').transact() ...