如何在pytest中使用参数化的依赖夹具两次？

Question

我试图在一次测试中多次使用参数化夹具，以获取所有值的笛卡尔积。

/sf/answers/2761086891/展示了如何通过简单的夹具进行此操作：

import pytest

@pytest.fixture(params=[0, 1, 2])
def first(request):
    return request.param

second = first

# runs 3x3 = 9 times
def test_double_fixture(first, second):
    assert False, '{} {}'.format(first, second)

但是，如果参数化来自依赖的夹具，则此方法会瓦解：

import pytest

@pytest.fixture(params=[0, 1, 2])
def integer(request):
    return request.param

@pytest.fixture
def squared_integer(integer):
    return integer * integer

@pytest.fixture
def first(squared_integer):
    return squared_integer

second = first

# runs only 3 times
def test_double_fixture(first, second):
    assert False, '{} {}'.format(first, second)

我如何像简单的示例一样进行3x3运行测试？

Answer 1

这是 pytest 的正确行为。因为您integer在其他装置的深处使用。要了解发生的情况，请使用 --setup-show 标志检查 pytest。你会看到类似的东西：

        SETUP    F integer[0]
        SETUP    F squared_integer (fixtures used: integer)
        SETUP    F first (fixtures used: squared_integer)
        SETUP    F second (fixtures used: squared_integer)
        Test/test_54044536_3.py::test_double_fixture[0] (fixtures used: first, integer, second, squared_integer)F
        TEARDOWN F second
        TEARDOWN F first
        TEARDOWN F squared_integer
        TEARDOWN F integer[0]

因此整数值仅适用于 squared_integer 函数。

为了回答您的问题，我们可以将您的代码重构为固定装置和一个函数。这看起来像：

        SETUP    F integer[0]
        SETUP    F squared_integer (fixtures used: integer)
        SETUP    F first (fixtures used: squared_integer)
        SETUP    F second (fixtures used: squared_integer)
        Test/test_54044536_3.py::test_double_fixture[0] (fixtures used: first, integer, second, squared_integer)F
        TEARDOWN F second
        TEARDOWN F first
        TEARDOWN F squared_integer
        TEARDOWN F integer[0]

您将进行 9 次测试，顺序如下：

        SETUP    F first[0]
        SETUP    F second[0]
        Test/test_54044536_2.py::test_double_fixture[0-0] (fixtures used: first, second)F
        TEARDOWN F second[0]
        TEARDOWN F first[0]
        SETUP    F first[0]
        SETUP    F second[1]
        Test/test_54044536_2.py::test_double_fixture[0-1] (fixtures used: first, second)F
        TEARDOWN F second[1]
        TEARDOWN F first[0]
        SETUP    F first[0]
        SETUP    F second[2]
        Test/test_54044536_2.py::test_double_fixture[0-2] (fixtures used: first, second)F
        TEARDOWN F second[2]
        TEARDOWN F first[0]
        SETUP    F first[1]
        SETUP    F second[0]
        Test/test_54044536_2.py::test_double_fixture[1-0] (fixtures used: first, second)F
        TEARDOWN F second[0]
        TEARDOWN F first[1]
        SETUP    F first[1]
        SETUP    F second[1]
        Test/test_54044536_2.py::test_double_fixture[1-1] (fixtures used: first, second)F
        TEARDOWN F second[1]
        TEARDOWN F first[1]
        SETUP    F first[1]
        SETUP    F second[2]
        Test/test_54044536_2.py::test_double_fixture[1-2] (fixtures used: first, second)F
        TEARDOWN F second[2]
        TEARDOWN F first[1]
        SETUP    F first[2]
        SETUP    F second[0]
        Test/test_54044536_2.py::test_double_fixture[2-0] (fixtures used: first, second)F
        TEARDOWN F second[0]
        TEARDOWN F first[2]
        SETUP    F first[2]
        SETUP    F second[1]
        Test/test_54044536_2.py::test_double_fixture[2-1] (fixtures used: first, second)F
        TEARDOWN F second[1]
        TEARDOWN F first[2]
        SETUP    F first[2]
        SETUP    F second[2]
        Test/test_54044536_2.py::test_double_fixture[2-2] (fixtures used: first, second)F
        TEARDOWN F second[2]
        TEARDOWN F first[2]