这与以前的问题基本相同,但希望现在有更好的解决方案。
问题:给定一个参数化的fixture,如何用fixture对象的子集来参数化测试函数?
示例:
import pytest
@pytest.fixture(params=range(7))
def square(request):
return request.param ** 2
def test_all_squares(square):
sqrt = square ** 0.5
assert sqrt == int(sqrt)
@pytest.fixture()
def odd_square(square):
if square % 2 == 1:
return square
pytest.skip()
def test_all_odd_squares(odd_square):
assert odd_square % 2 == 1
sqrt = odd_square ** 0.5
assert sqrt == int(sqrt)
输出:
$pytest-pytests.py-v====================================================测试会话开始================================。。。收集了14个项目pytests.py::test_all_squares[0]通过[7%]pytests.py::test_all_squares[1]通过[14%]pytests.py::test_all_squares[2]通过[21%]pytests.py::test_all_squares[3]通过[28%]pytests.py::test_all_squares[4]通过[35%]pytests.py::test_all_squares[5]通过[42%]pytests.py::test_all_squares[6]通过[50%]pytests.py::test_all_odd_squares[0]跳过[57%]pytests.py::test_all_odd_squares[1]通过[64%]pytests.py::test_all_odd_squares[2]跳过[71%]pytests.py::test_all_odd_squares[3]通过[78%]pytests.py::test_all_odd_squares[4]跳过[85%]pytests.py::test_all_odd_squares[5]通过[92%]pytests.py::test_all_odd_squares[6]跳过[100%]==============================================10通过,4在0.02秒内跳过================================
尽管这很有效,但并不理想:
- 它创建了总是被跳过的伪测试用例
- 它需要使用过滤的fixture为参数提供不同名称(
odd_square
(的测试函数
我想要的是一个filter_fixture(predicate, fixture)
函数,它过滤原始夹具的对象,并可以传递给pytest.mark.parametrize
,类似于以下内容:
@pytest.mark.parametrize("square", filter_fixture(lambda x: x % 2 == 1, square))
def test_all_odd_squares(square):
assert square % 2 == 1
sqrt = square ** 0.5
assert sqrt == int(sqrt)
这在某种程度上可行吗?
如果您需要一定程度的逻辑来确定将哪些参数应用于每个测试,您可能需要考虑使用pytest_generate_tests
挂钩。
钩子函数pytest_generate_tests
是为每个收集的测试调用的。metafunc
参数允许您动态地参数化每个单独的测试用例。重写您的示例以使用pytest_generate_tests
可能如下所示:
def pytest_generate_tests(metafunc):
square_parameters = (x**2 for x in range(7))
if 'square' in metafunc.fixturenames:
metafunc.parametrize("square", square_parameters)
if 'odd_square' in metafunc.fixturenames:
odd_square_parameters = (x for x in square_parameters if x % 2 == 1)
metafunc.parametrize("odd_square", odd_square_parameters)
def test_all_squares(square):
sqrt = square ** 0.5
assert sqrt == int(sqrt)
def test_all_odd_squares(odd_square):
assert odd_square % 2 == 1
sqrt = odd_square ** 0.5
assert sqrt == int(sqrt)
这导致运行以下测试用例:
$ pytest -v pytests.py
=========== test session starts ===========
…
collected 10 items
pytests.py::test_all_squares[0] PASSED [ 10%]
pytests.py::test_all_squares[1] PASSED [ 20%]
pytests.py::test_all_squares[4] PASSED [ 30%]
pytests.py::test_all_squares[9] PASSED [ 40%]
pytests.py::test_all_squares[16] PASSED [ 50%]
pytests.py::test_all_squares[25] PASSED [ 60%]
pytests.py::test_all_squares[36] PASSED [ 70%]
pytests.py::test_all_odd_squares[1] PASSED [ 80%]
pytests.py::test_all_odd_squares[9] PASSED [ 90%]
pytests.py::test_all_odd_squares[25] PASSED [100%]
=========== 10 passed in 0.03s ===========
请注意,我的示例中的测试ID与您的略有不同。但是,可以使用metafunc.parametrize
的ìds
参数提供显式测试标识符。