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Testing & modern typing

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

3 matches

How to Compare Floats in pytest with approx

Uses pytest.approx to compare floating-point numbers with tolerance, avoiding precision issues.

import pytest

def test_float_addition():
    result = 0.1 + 0.2
    expected = 0.3
    assert result == pytest.approx(expected)

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Testing & modern typing easy

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 Use Union Type Hints in Python

This code demonstrates how to use Union type hints to specify that a parameter can accept multiple types (int, float, str) and handle them accordingly.

type-hints union typing

Python

from typing import Union

def process_value(value: Union[int, float, str]) -> str:
    if isinstance(value, (int, float)):
        return f"Number: {value * 2}"
    return f"String: {value.upper()}"

if __name__ == "__main__":
    print(process_value(10))
    print(process_value(3.14))
    print(process_value("hello"))

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