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Testing & modern typing

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

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How to Merge TypedDicts in Python

Merge two TypedDict dictionaries with type-aware logic using NotRequired, **kwargs unpacking, and safe key updates.

from typing import TypedDict, NotRequired, merge  # hypothetical

class User(TypedDict):
    name: str
    email: NotRequired[str]
    age: NotRequired[int]

def merge_users(base: User, **overrides: User) -> User:
    """Merge two user dicts with typing-aware logic."""
    result: User = dict(base)
    for key, value …

13 0 Open

Testing & modern typing easy

How to Mock requests.get in Python

Mock requests.get with unittest.mock to test code that makes HTTP calls without hitting the network.

mocking requests unit-testing

Python

import requests
from unittest.mock import Mock, patch

def fetch_user_data(user_id):
    response = requests.get(f"https://api.example.com/users/{user_id}")
    return response.json()

def process_user(user_id):
    mock_response = Mock()
    mock_response.json.return_value = {"id": user_id, "name": "Alice", "age": 30…

12 0 Open

Testing & modern typing easy

How to Sort Data in Python

Sort sequences with type-safe helpers that handle mixed data with a string fallback.

sorting typing protocol

Python

from typing import Any, TypeVar, Protocol, Sequence, Iterable

T = TypeVar("T")
Comparable = TypeVar("Comparable", bound="Comparable")

class Sortable(Protocol):
    def __lt__(self, other: Any) -> bool: ...

S = TypeVar("S", bound=Sortable)

def sort_data(data: Sequence[S], *, reverse: bool = False) -> list[S]:
    "…

14 0 Open

Testing & modern typing easy

How to Write a pytest Test Function with assert Equal in Python

Define simple pytest test functions that use assert to verify result equality and run them with pytest.main.

pytest unit testing assert

Python

import pytest

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

def test_add_positive_numbers():
    result = add(2, 3)
    assert result == 5

def test_add_negative_numbers():
    result = add(-2, -3)
    assert result == -5

def test_add_mixed_numbers():
    result = add(2, -3)
    assert result == -1

if __name__ == "__main__":
  …

11 0 Open

Testing & modern typing easy

How to Write pytest Test Function Assert Equal in Python

Write three pytest test functions that assert the result of an add() function equals an expected numeric value.

pytest assert testing

Python

import pytest

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

def test_add_positive_numbers():
    assert add(2, 3) == 5

def test_add_negative_numbers():
    assert add(-1, -2) == -3

def test_add_mixed_numbers():
    assert add(5, -3) == 2

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

12 0 Open

Testing & modern typing easy

How to use unittest mock side_effect with a sequence in Python

Demonstrates using Mock.side_effect with a list to return different values per call and raise an exception at a specific call in unittest.

unittest mock side_effect

Python

import unittest
from unittest.mock import Mock

class TestMockSideEffectSequence(unittest.TestCase):
    def test_side_effect_sequence(self):
        mock = Mock()
        mock.side_effect = [1, 2, 3, Exception("boom")]
        
        self.assertEqual(mock(), 1)
        self.assertEqual(mock(), 2)
        self.asser…

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