Python mock Patch os.environ and return value

Question

Unit testing conn() using mock:

app.py

import mysql.connector
import os, urlparse


def conn():
    if "DAT         


        

Answer 1

For this, I find that pytest's monkeypatch fixture leads to better code when you need to set environment variables:

def test_conn(monkeypatch):
    monkeypatch.setenv('DATABASE_URL', '')
    with patch(app.mysql.connector) as mock_mysql:
        conn()
    mock_mysql.connect.assert_called_with()