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Testing & modern typing

pytest basics, mocks, type hints, TypedDict, Protocol, and static-checking patterns.

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Generate Fake User Data with Faker in Python

Use the Faker library to generate realistic fake user profiles with names, emails, phone numbers, and addresses for tests or demos.

faker fake-data testing

Python

from faker import Faker

fake = Faker()

def generate_user():
    return {
        "name": fake.name(),
        "email": fake.email(),
        "phone": fake.phone_number(),
        "address": fake.address().replace("\n", ", "),
    }

if __name__ == "__main__":
    user = generate_user()
    for key, value in user.ite…

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Testing & modern typing easy

How to Parametrize pytest Tests with Multiple Input Cases in Python

This code shows how to use pytest's @pytest.mark.parametrize decorator to run the same test function across multiple input-output combinations, checking that an add function behaves correctly for each case.

pytest parametrize testing

Python

import pytest

def add(a, b):
    return a + b


@pytest.mark.parametrize("a,b,expected", [
    (1, 2, 3),
    (5, 5, 10),
    (-1, 1, 0),
    (0, 0, 0),
    (10, -3, 7),
])
def test_add(a, b, expected):
    assert add(a, b) == expected


if __name__ == "__main__":
    pytest.main([__file__, "-v"])

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Testing & modern typing easy

How to Share Fixtures Across Tests with pytest conftest

Learn how to define pytest fixtures in conftest.py and control their scope (function, module, session) so every test in a directory reuses the same setup and teardown.

pytest fixtures conftest

Python

import pytest

@pytest.fixture
def sample_data():
    """Simple fixture available to all tests in this directory."""
    return {"name": "Alice", "age": 30}

@pytest.fixture(scope="session")
def session_data():
    """Fixture created once per test session."""
    return {"session_id": 12345}

@pytest.fixture(scope="mo…

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Testing & modern typing easy

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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Testing & modern typing easy

How to Use mock.assert_called_with in Python

Verify that a MagicMock received a call with specific positional and keyword arguments using assert_called_with in unittest.

unittest mock testing

Python

import unittest
from unittest.mock import MagicMock

class TestMockAssertions(unittest.TestCase):
    def test_assert_called_with(self):
        # Create a mock object
        mock = MagicMock()

        # Call the mock with specific arguments
        mock.send_email("alice@example.com", subject="Greetings", body="Hel…

14 0 Open

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