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Testing & modern typing

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How to Test Environment Variables with pytest monkeypatch in Python

Shows how to use pytest's monkeypatch fixture to set and delete environment variables for isolated tests.

pytest monkeypatch environment variables
Python 
import os
import pytest

def get_database_url():
    return os.getenv("DATABASE_URL", "postgres://default")

def test_database_url_with_env(monkeypatch):
    monkeypatch.setenv("DATABASE_URL", "postgres://test-db")
    assert get_database_url() == "postgres://test-db"

def test_database_url_default(monkeypatch):
    m…
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