如何创建使用 `builds()` 的可配置自定义假设策略？

Question

我使用 builds() and @composite (the design is inspired by this example from the docs) 创建了自定义假设策略。这些策略的设计类似于下面的伪代码：

# strategies.py

from hypothesis.strategies import builds, composite, draw, floats, integers

class SutConfiguration:
    """ Data which represents the configuration of the system under test. """
    def __init__(self, integer, float):
        self.integer = integer
        self.float = float

# custom strategy which uses builds()
SutConfigurationStrategy = builds(
    SutConfiguration,
    integer=integers(min_value=APP_SPECIFIC_INT_MIN, max_value=APP_SPECIFIC_INT_MAX),
    float=floats(min_value=APP_SPECIFIC_FLOAT_MIN, max_value=APP_SPECIFIC_FLOAT_MAX),
)

@composite
def overall_test_configuration(draw, sut_st=SutConfigurationStrategy, env_st=SutEnvironmentStrategy):
    """Custom strategy which uses draw."""
    sut_config = draw(sut_st)
    env_config = draw(env_st)
    return (sut_config, rc_stereomatching_config, env_config)

该策略照常使用，例如使用 unittest 作为测试运行器：

# test.py

import unittest
from <package>.strategies import overall_test_configuration

class TestSut(unittest.TestCase):
    """Class containing several tests for the system under test."""
    @given(overall_test_configuration())
    def test_something():
        """Test which uses overall_test_configuration"""
        ...

现在我想让策略可配置到实际应用程序来定义例如min_value in integers(min_value=APP_SPECIFIC_INT_MIN, ...) 定义测试函数时。这可以通过 done here 等参数为 @composite 策略完成。但是如何使使用 builds() 的策略可配置？

Answer 1

您可以定义一个函数，returns 像任何其他策略一样的策略：

def some_custom_strategy(a, b):
    return builds(foo, bar(a, b))

当你有额外的参数时，这就是 composite 发生的所有事情 - composite 正在定义一个函数，returns 一个策略，这些额外的参数通过函数传递给底层装饰函数。

Answer 2

应用于上述伪代码的解决方案，例如SUT 配置 SutConfigurationStrategy 可配置的整数值如下所示：

# strategies.py

from hypothesis.strategies import builds, composite, draw, floats, integers

class SutConfiguration:
    """ Data which represents the configuration of the system under test. """
    def __init__(self, integer, float):
        self.integer = integer
        self.float = float

# custom strategy which uses builds()
def SutConfigurationStrategy(min_int_config, max_int_config):
    return builds(SutConfiguration,
                  integer=integers(min_value=min_int_config, max_value=max_int_config),
                  float=floats(min_value=APP_SPECIFIC_FLOAT_MIN, max_value=APP_SPECIFIC_FLOAT_MAX),
)

@composite
def overall_test_configuration(draw, sut_min_int_config, sut_max_int_config, sut_st=SutConfigurationStrategy, env_st=SutEnvironmentStrategy):
    """Custom strategy which uses draw."""
    sut_config = draw(sut_st(sut_min_int_config, sut_max_int_config))
    env_config = draw(env_st)
    return (sut_config, rc_stereomatching_config, env_config)

策略整数值然后可以例如配置为 10 的最小值和 100 的最大值（再次：unittest 作为测试运行器）：

# test.py

import unittest
from <package>.strategies import overall_test_configuration

class TestSut(unittest.TestCase):
    """Class containing several tests for the system under test."""
    @given(overall_test_configuration(min_int_config=10, max_int_config=100))
    def test_something():
        """Test which uses overall_test_configuration"""
        ...

旁注：这里使用class SutConfiguration来封装数据并不是最优的。 Namedtuple 在这里是更好的选择...

如何创建使用 `builds()` 的可配置自定义假设策略？

How can I create configurable custom hypothesis strategies which use `builds()`?

python

python-hypothesis