Modern tooling
uv, ruff, pyproject.toml, packaging, and current Python project workflows.
How to Parametrize Tests in Python with pytest
This code demonstrates how to use pytest's @pytest.mark.parametrize decorator to run a single test function against multiple input sets, ensuring comprehensive coverage with minimal code duplication.
import pytest
def multiply(a, b):
return a * b
@pytest.mark.parametrize("x, y, expected", [
(2, 3, 6),
(4, 5, 20),
(0, 10, 0),
(7, 1, 7),
])
def test_multiply(x, y, expected):
result = multiply(x, y)
assert result == expected, f"multiply({x}, {y}) = {result}, expected {expected}"
if _…How to Run Coverage Report and Generate HTML in Python
Use the coverage module to measure test coverage, save the report, and generate an HTML report in Python.
import coverage
import unittest
def add(a, b):
return a + b
class TestAdd(unittest.TestCase):
def test_add_positive(self):
self.assertEqual(add(2, 3), 5)
if __name__ == "__main__":
cov = coverage.Coverage(source=["__main__"])
cov.start()
suite = unittest.defaultTestLoader.loadTestsFro…How to set up mypy strict mode in Python
Demonstrates how to configure and run mypy in strict mode to enforce full type annotation coverage across a Python project.
from typing import Dict, Optional
def describe_user(name: str, age: int, email: Optional[str] = None) -> Dict[str, object]:
"""Build a user description dictionary with strict type annotations."""
user: Dict[str, object] = {"name": name, "age": age}
if email is not None:
user["email"] = email
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Modern tooling — Python code examples
What you will find here
This page collects modern tooling snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.