Use property tests for parsers

Эта статья ещё не доступна на языке «Русский»; показан оригинал.

methodology · en · актуально на 2026-09-21 · изменено 2026-09-23, ревизия 3 · reviewed (рецензия задокументирована 2026-09-23)

Express parser invariants over generated inputs and keep minimized failures as focused regression examples.

Choose a real invariant

A useful property describes intended behavior, not merely that the function does not raise. For a serializer/parser pair over an explicitly supported domain, a candidate property is parse(serialize(value)) == value. Define the domain before generating values.

Example with Hypothesis

import json
from hypothesis import given, strategies as st

@given(st.lists(st.integers(), max_size=30))
def test_integer_list_roundtrip(values):
    assert json.loads(json.dumps(values)) == values

Hypothesis generates examples and seeks smaller failing examples. This fixture is an illustration of the method, not evidence that an arbitrary parser is correct.

Expand deliberately

Add malformed inputs, size limits and ambiguous encodings as separate properties or examples. A parser and serializer can share the same bug, so include independent known-answer cases where practical. Preserve a minimized failure as a readable regression test.

Limits

Constrain generated inputs to avoid uncontrolled resource consumption. A passing run covers the generated examples, not every possible input, and permissive generation can accidentally exclude the very boundary that matters. Review the strategy and property alongside the parser implementation.

Область и основание

Original worked method and proposed acceptance fixtures; no empirical performance result is claimed. The cited primary documentation was read for the specific technical behavior described.

Актуально на: 2026-09-21. Статус: reviewed — правки сбрасывают статус рецензии. Считайте текст непроверенным справочным материалом и сверяйтесь с источниками.

Источники

Рецензия

Задокументированная рецензия ревизии 3 аккаунтом редактора 344519e7-8ea1-44c6-abaa-29102abda2b6 от 2026-09-23. Относится к текущей ревизии: да.

Operator review: article written by an account of the operator (MK Groups Schweiz) and accepted as reviewed by the operator.

Operator decision of 2026-09-23 that the operator's own curated articles count as reviewed; each cited source was fetched at import time and the quoted phrase was found on the page. No independent third-party review is claimed.

Задокументированная рецензия фиксирует, что было проверено; она не гарантирует истинность.

Атрибуция и лицензия

Последнее изменение: Replaced generic draft with a specific procedure, example, failure cases and correctly scoped sources; removed unrelated product applicability.

Оригинальный материал: CC BY 4.0. Материалы по ссылкам сохраняют собственные права.