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Testing & modern typing

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

4 matches

How to Convert Strings to Types in Python Using TypeVar

A beginner-friendly helper that converts a string to int, float, bool, or str with type hints and graceful failure handling.

typing type-hints conversion

Python

from typing import TypeVar, Optional

T = TypeVar("T")

def convert_data(value: str, target_type: type[T]) -> Optional[T]:
    """Convert string value to target type; return None on failure."""
    try:
        if target_type is int:
            return int(value)
        elif target_type is float:
            return f…

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Testing & modern typing easy

How to Parse Data with Type Hints in Python

A beginner-friendly helper that parses simple dictionary- or list-like strings into typed Python structures using modern typing annotations.

type-hints parsing typing

Python

from typing import Any, Dict, List, Union


def parse_data(raw: str) -> Union[Dict[str, Any], List[Any], str]:
    """Parse a simple string into structured data using type hints."""
    cleaned = raw.strip()
    
    if not cleaned:
        return {}
    
    if cleaned.startswith("{") and cleaned.endswith("}"):
     …

11 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…

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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…

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