python - 你如何使用 Hypothesis @given 参数化一个 pytest 类？

Question

为了测试当我添加两个非常相似的数据行时我的数据库的行为，我需要为每个参数组合设置一个新数据库。我还使用 Hypothesis 的策略来生成“相似”的数据行。
测试工作流程应如下所示:

for example in hypothesis-given-examples:    # @given
    for combination in pytest-parametrized-combinations:   # @pytest.mark.parametrize
        db = setup_db(example, combination)  # should be a fixture with `yield` but I can't parametrize it
        do_test_1(db)  # using the setup database
        do_test_2(db)  # using the setup database
        do_test_3(db)  # using the setup database
        teardown(db)

我开始于:

@mark.parametrize('different_properties', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'])
@mark.parametrize('different_identproperties', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'])
@mark.parametrize('different_labels', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'])
class TestMerge:
    @classmethod
    @given(node1=node_strategy, sampler=data())
    def setup_class(cls, node1, sampler, different_labels, different_properties, different_identproperties):
        node2 = create_node_from_node(node1, sampler, different_labels, different_properties,
                                      different_identproperties)  # uses hypothesis to generate
        cls.node1, cls.node2 = node1, node2

    def test_merge(self):
        read_node1, read_node2 = read(1), read(2)
        # do some test here comparing input and output

但似乎不可能进行这样的设置
因此，我尝试使用带有间接参数的 fixture ，但我想对整个类执行此操作，并且为每个测试方法复制参数似乎很荒谬，而且我无法使用提供的间接参数制作参数列表的笛卡尔积到一个 fixture 。
这是一个最小的运行/错误示例:

import pytest
from hypothesis import strategies as st
from hypothesis import given

@pytest.mark.parametrize('different_properties', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'], scope='class')
@pytest.mark.parametrize('different_identproperties', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'], scope='class')
@pytest.mark.parametrize('different_labels', [False, 'entirekeys', 'crop', 'addkeys', 'overwritekeys'], scope='class')
class TestMerge:
    @classmethod
    @given(node1=st.integers(), sampler=st.data())
    def setup_class(cls, node1, sampler, different_labels, different_properties, different_identproperties):
        node2 = node1 * 2  # just for the minimal example
        cls.node1, cls.node2 = node1, node2

    def test_merge(self, different_labels, different_properties, different_identproperties):
        # read_node1, read_node2 = read(1), read(2)
        # do some test here comparing input and output
        pass

pytest 输出:

ERROR test_minimal_example.py::TestMerge::test_merge[False-False-False] - TypeError: setup_class() missing 3 required...
ERROR test_minimal_example.py::TestMerge::test_merge[False-False-entirekeys] - TypeError: setup_class() missing 3 req...
    ...

希望你能看到我在做什么。如果没有，请问!
谢谢!

Answer 1

不清楚你为什么在这里使用一个类。尝试例如

@pytest.mark.parametrize("p1", [True, False])
@pytest.mark.parametrize("p2", [True, False])
@given(ex=st.integers())
def test(p1, p2, ex):
    with setup_db(ex, (p1, p2)) as db:
        do_test_1(db)
        do_test_2(db)
        do_test_3(db)

(请注意，如果您在适当的位置添加 self，这也适用于测试方法)