[Python] Cannot mock python function called during import

I am trying to mock a sqlalchemy create_engine method called during import of a python script. But I am not able to properly do so. Here is my file structure:

File main.py

from database_wrapper import update_database

def do_something():
# do something and
update_database()


database_wrapper.py

from sqlalchemy import create_engine

engine = create_engine("connection_uri")


def update_database() -> bool:

con = engine.connect()
# do something with the connection, and so on...


In my test unit i do something like:


class TestMicroservice(TestCase):

@patch('database_wrapper.create_engine')
@patch('main.update_database')
def test_1(self, update_database_mock, create_engine_mock):

create_engine_mock.return_value = "Fake engine, babe"
update_database_mock.return_value = True

from main import do_something

do_something()


I have also tried @patch('main.database_wrapper.create_engine'), @patch('main.database_wrapper.sqlalchemy.create_engine'), @patch('sqlalchemy.create_engine') and many other variations but with no luck. I have read a few similar posts but couldn't find this exact case. I would rather avoid changing database_wrapper.py, hence i cannot move engine = create_engine("connection_uri"). Also because I am happy to create the engine when the program start without having to pass it around.

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