pytest-evm

The testing package containing tools to test Web3-based projects

• Bug reports

Package's source code is made available under the MIT License

The project is made by the Croco Factory team

Quick Start

There are few features simplifying your testing with pytest:

• Fixtures
• Test Reporting
• Usage Example

Fixtures

make_wallet

This fixture simplify creating wallet instances as fixtures. Wallet instances are from evm-wallet package

import os
import pytest
from typing import Optional
from evm_wallet.types import NetworkInfo
from evm_wallet import AsyncWallet, Wallet

@pytest.fixture(scope="session")
def make_wallet():
    def _make_wallet(network: NetworkOrInfo, private_key: Optional[str] = None, is_async: bool = True):
        if not private_key:
            private_key = os.getenv('TEST_PRIVATE_KEY')
        return AsyncWallet(private_key, network) if is_async else Wallet(private_key, network)

    return _make_wallet

You can specify whether your wallet should be of async or sync version. Instead of specifying RPC, you only have to provide chain's name. You can also specify a custom Network, using NetworkOrInfo.

import pytest

@pytest.fixture
def wallet(make_wallet):
    return make_wallet('Optimism')

As you can see, a private key wasn't passed. This because of by-default make_wallet takes it from environment variable TEST_PRIVATE_KEY. You can set environment variables using extra-package python-dotenv.

# conftest.py

import pytest
from dotenv import load_dotenv

load_dotenv()


@pytest.fixture(scope="session")
def wallet(make_wallet):
    return make_wallet('Polygon')

Here is the content of .env file

# .env

TEST_PRIVATE_KEY=0x0000000000000000000000000000000000000000

You can install python-dotenv along with pytest-evm:

pip install pytest-evm[dotenv]

zero_address

This fixture returns ZERO_ADDRESS value

import pytest
from evm_wallet import ZERO_ADDRESS

@pytest.fixture(scope="session")
def zero_address():
    return ZERO_ADDRESS

eth_amount

This fixture returns 0.001 ETH in Wei, which is the most using minimal value for tests

import pytest
from web3 import AsyncWeb3

@pytest.fixture(scope="session")
def eth_amount():
    amount = AsyncWeb3.to_wei(0.001, 'ether')
    return amount

Test Reporting

If your want to test one transaction, you can automatically assert transaction status and get useful report after test, if it completed successfully. To do this, you need to add mark pytest.mark.tx to your test and you must return transaction hash in test

import pytest

@pytest.mark.tx
@pytest.mark.asyncio
async def test_transaction(wallet, eth_amount):
    recipient = '0xe977Fa8D8AE7D3D6e28c17A868EF04bD301c583f'
    params = await wallet.build_transaction_params(eth_amount, recipient=recipient)
    return await wallet.transact(params)

After test, you get similar report:

Usage Example

Here is example of testing with pytest-evm:

import pytest
from bridge import Bridge

class TestBridge:
    @pytest.mark.tx
    @pytest.mark.asyncio
    async def test_swap(self, wallet, eth_amount, bridge, destination_network):
        return await bridge.swap(eth_amount, destination_network)

    @pytest.mark.tx
    @pytest.mark.asyncio
    async def test_swap_to_eth(self, wallet, eth_amount, bridge):
        return await bridge.swap_to_eth(eth_amount)

    @pytest.fixture
    def wallet(self, make_wallet):
        return make_wallet('Optimism')

    @pytest.fixture
    def bridge(self, wallet):
        return Bridge(wallet)

    @pytest.fixture
    def destination_network(self):
        return 'Arbitrum'

Installing pytest-evm

To install the package from GitHub you can use:

pip install git+https://github.com/CrocoFactory/pytest-evm.git

To install the package from PyPi you can use:

pip install pytest-evm