স্টাব ও ফেক বাস্তবে ব্যবহার

import unittest
from unittest.mock import Mock


def should_carry_umbrella(city, weather_client):
    forecast = weather_client.get_forecast(city)
    return forecast["rain_chance"] >= 50


class UmbrellaAdviceTests(unittest.TestCase):
    def test_high_rain_chance_recommends_umbrella(self):
        stub_client = Mock()
        stub_client.get_forecast.return_value = {"rain_chance": 80}
        self.assertTrue(should_carry_umbrella("Dhaka", stub_client))

    def test_low_rain_chance_no_umbrella(self):
        stub_client = Mock()
        stub_client.get_forecast.return_value = {"rain_chance": 10}
        self.assertFalse(should_carry_umbrella("Dhaka", stub_client))

    def test_api_failure_propagates_via_side_effect(self):
        stub_client = Mock()
        stub_client.get_forecast.side_effect = ConnectionError("Weather API নামানো যায়নি")
        with self.assertRaises(ConnectionError):
            should_carry_umbrella("Dhaka", stub_client)


suite = unittest.TestLoader().loadTestsFromTestCase(UmbrellaAdviceTests)
unittest.TextTestRunner(verbosity=2).run(suite)

import unittest


class FakeUserRepository:
    """ফেক — বাস্তব ডেটাবেসের বদলে in-memory dict, কিন্তু আসলেই কাজ করে।"""
    def __init__(self):
        self._data = {}

    def save(self, user_id, name):
        self._data[user_id] = name

    def get(self, user_id):
        return self._data.get(user_id)

    def exists(self, user_id):
        return user_id in self._data


def register_and_greet(user_id, name, repository):
    if repository.exists(user_id):
        return f"{name} ইতিমধ্যে নিবন্ধিত"
    repository.save(user_id, name)
    return f"স্বাগতম, {name}!"


class RegisterAndGreetTests(unittest.TestCase):
    def setUp(self):
        self.repo = FakeUserRepository()  # প্রতিটি টেস্টের আগে একদম নতুন, খালি ফেক রিপোজিটরি

    def test_new_user_registers_and_is_saved(self):
        result = register_and_greet(1, "নাদিয়া", self.repo)
        self.assertEqual(result, "স্বাগতম, নাদিয়া!")
        self.assertTrue(self.repo.exists(1))
        self.assertEqual(self.repo.get(1), "নাদিয়া")

    def test_existing_user_not_re_registered(self):
        self.repo.save(2, "ফারহান")
        result = register_and_greet(2, "ফারহান", self.repo)
        self.assertEqual(result, "ফারহান ইতিমধ্যে নিবন্ধিত")


suite2 = unittest.TestLoader().loadTestsFromTestCase(RegisterAndGreetTests)
unittest.TextTestRunner(verbosity=2).run(suite2)