这基本上与老问题 https://stackoverflow.com/questions/47696002/chaining-pytest-fixtures但希望现在有更好的解决方案。
问题：给定一个参数化夹具，如何使用夹具对象的子集参数化测试函数？
Example:
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)
Output:
$ pytest pytests.py -v
=================================================================== test session starts ===================================================================
...
collected 14 items
pytests.py::test_all_squares[0] PASSED [ 7%]
pytests.py::test_all_squares[1] PASSED [ 14%]
pytests.py::test_all_squares[2] PASSED [ 21%]
pytests.py::test_all_squares[3] PASSED [ 28%]
pytests.py::test_all_squares[4] PASSED [ 35%]
pytests.py::test_all_squares[5] PASSED [ 42%]
pytests.py::test_all_squares[6] PASSED [ 50%]
pytests.py::test_all_odd_squares[0] SKIPPED [ 57%]
pytests.py::test_all_odd_squares[1] PASSED [ 64%]
pytests.py::test_all_odd_squares[2] SKIPPED [ 71%]
pytests.py::test_all_odd_squares[3] PASSED [ 78%]
pytests.py::test_all_odd_squares[4] SKIPPED [ 85%]
pytests.py::test_all_odd_squares[5] PASSED [ 92%]
pytests.py::test_all_odd_squares[6] SKIPPED [100%]
============================================================== 10 passed, 4 skipped in 0.02s ==============================================================
虽然这有效，但并不理想：
- 它创建总是被跳过的虚拟测试用例
- 它需要使用过滤后的夹具来给出不同名称的测试函数（
odd_square) 到参数。
我想要的是例如Afilter_fixture(predicate, fixture)过滤原始灯具对象的函数，可以传递给pytest.mark.parametrize，像这样：
@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 hook. https://docs.pytest.org/en/latest/how-to/parametrize.html#basic-pytest-generate-tests-example
钩子函数pytest_generate_tests每个收集的测试都会被调用。这metafuncargument 允许您动态参数化每个单独的测试用例。重写您的示例以使用pytest_generate_tests可能看起来像这样：
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)
这会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，您可以使用以下方法提供显式测试标识符ìds的论证metafunc.parametrize.
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