[Python] How to mock an Enum in pytest globally

I have a trading bot project, let's call it trading_bot. I am using python-binance. I have an enum

class CoinName(str, Enum):
USDT = "USDT"

BTC = "BTC"
ETH = "ETH"
BNB = "BNB"
XRP = "XRP"
ADA = "ADA"
...


which consists of 100 coin names. I am using it for type hinting, but also via list(CoinName) to iterate over the coins I am interested to send requests, to get historical prices and to filter my current assets. I want to only use a subset of it for the tests. I am using pytest and pytest-mock.

I have a mock like this:

@pytest.fixture
def mock_binance_client(mocker):
mock_client = MockBinanceClient()
mocker.patch("binance.Client", return_value=mock_client)

return mock_client


This is okay as in the tests I use it directly or inject it explicitly. However, I am struggling to mock CoinName.

So far I found two solutions:

In conftest.py:

def pytest_configure(config):
from pytest_mock import plugin
mocker = plugin.MockerFixture(config)

mock_definitions = mocker.Mock()
mock_definitions.CoinName = MockCoinName

mocker.patch.dict(
"sys.modules", {"trading_bot.definitions": mock_definitions})


or I need to add from trading_bot.definitions import CoinName to my project __init__.py and everywhere I do from trading_bot.definitions import CoinName I have to change it to import trading_bot and then use it via trading_bot.CoinName. Then if in conftest.py I mock normally:

@pytest.fixture(autouse=True)
def mock_coin_name(mocker):
patched = mocker.patch(
"trading_bot.definitions.CoinName", MockCoinName)


It works.

However, it doesn't work if I do the second option and don't change my importing method, as then other files have another linking to CoinName, via trading_bot.foo.CoinName and this gets imported before any fixture runs.

My question: The first solution feels too hacky and the second one feels too cumbersome. Is there a way to not change how I import in my project but also not hack sys.modules directly and mock the enum? Or should I structure my code differently, for example not use enums like this?

Thank you in advance.

Continue reading...