Reference library

Testing & modern typing

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

4 matches

How to Use Basic Type Hints (int, str) for Return Values in Python

Declare a simple function with int and str type hints and a typed return value in Python.

def greet(name: str, age: int) -> str:
    return f"{name} is {age} years old."


if __name__ == "__main__":
    print(greet("Alice", 30))

12 0 Open

Testing & modern typing easy

How to Use TypedDict and Dataclasses in Python

Create typed data structures with TypedDict and dataclasses, then use them as helper functions for describing objects in a type-safe way.

typing typdict dataclass

Python

from typing import TypedDict, NotRequired, Optional
from dataclasses import dataclass


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


@dataclass
class Product:
    id: int
    title: str
    price: float = 0.0


def describe_user(user: User) -> str:
    age = user.get("age",…

12 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

Browse by section

Each section groups closely related Python snippets.