property-based-testing - 如何在 Python 假设中递归地生成布尔表达式？

Question

一般来说，我是 Python 的假设库和基于属性的测试的新手。我想使用以下语法生成任意嵌套的策略表达式：

（（A和B）或C）

我觉得递归策略是我想要的，但我很难理解如何使用它。我拥有的代码似乎只生成一个“级别”的表达。这是我所拥有的：

import unittest

from hypothesis import given
from hypothesis.strategies import text, composite, sampled_from, characters, recursive, one_of


def policy_expressions():
    return recursive(attributes(), lambda base_strategy: one_of(base_strategy, policy_expression()))

@composite
def policy_expression(draw):
    left = draw(attributes())
    right = draw(attributes())
    gate = draw(gates())
    return u' '.join((left, gate, right))


def attributes():
    return text(min_size=1, alphabet=characters(whitelist_categories='L', max_codepoint=0x7e))


def gates():
    return sampled_from((u'or', u'and'))


class TestPolicyExpressionSpec(unittest.TestCase):

    @given(policy_expression=policy_expressions())
    def test_policy_expression_spec(self, policy_expression):
        print policy_expression
        assert policy_expression # not empty

如何使用 Hypothesis 生成任意嵌套的策略表达式？

标签： property-based-testingpython-hypothesis

Answer 1

我认为这可能会做你想要的。

import unittest

from hypothesis import given
from hypothesis.strategies import text, composite, sampled_from, characters, recursive, one_of


def policy_expressions():
    return one_of(attributes(), policy_expression())

@composite
def policy_expression(draw):
    left = draw(policy_expressions())
    right = draw(policy_expressions())
    gate = draw(gates())
    return u' '.join((left, gate, right))


def attributes():
    return text(min_size=1, alphabet=characters(whitelist_categories='L', max_codepoint=0x7e))


def gates():
    return sampled_from((u'or', u'and'))


class TestPolicyExpressionSpec(unittest.TestCase):

    @given(policy_expression=policy_expressions())
    def test_policy_expression_spec(self, policy_expression):
        print policy_expression
        assert policy_expression # not empty

if __name__ == '__main__':
    unittest.main()