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Testing & modern typing

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

3 matches

How to Test Hypotheses with Property-Based Check in Python

A Python search that checks an integer property (palindrome divisible by digit sum) and returns the first counterexample within a range, with exactly reproduced output from the code.

hypothesis testing palindrome

Python

def is_property_satisfied(n):
    """
    Demonstrates a mathematically inspired property:
    checks whether n is both a palindrome and divisible by its digit sum.
    """
    s = str(n)
    if s != s[::-1]:
        return False
    digit_sum = sum(int(d) for d in s)
    return digit_sum != 0 and n % digit_sum == 0

…

10 0 Open

Testing & modern typing medium

How to Test Properties with Random Inputs in Python

Write a simple property-based test in Python using random string generation to verify that string invariants like reverse-twice identity and uppercase idempotence always hold.

property-based-testing random testing

Python

import random
import string


def generate_random_string(length: int) -> str:
    """Generate a random alphanumeric string of given length."""
    chars = string.ascii_letters + string.digits
    return "".join(random.choice(chars) for _ in range(length))


def reverse_twice_is_identity(s: str) -> bool:
    """Propert…

12 0 Open

Testing & modern typing medium

How to Use Hypothesis Strategies for Lists of Text in Python

Generate random lists of non-empty strings with Hypothesis and verify that joining them with a comma-and-space separator meets expected length and containment invariants.

hypothesis property-based-testing strategies

Python

from hypothesis import given, strategies as st
from hypothesis import example


@given(st.lists(st.text(min_size=1, max_size=10), min_size=1, max_size=5))
def test_joined_string_length(items):
    """Each text is non-empty; a joined string should be at least as long
    as the number of items (separator adds character…

13 0 Open

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