python - 使用 pytest 的参数化，如果一个测试用例失败，我如何跳过剩余的测试？

Question

我pytest.mark.parametrize用来将越来越长的输入输入到一个相当慢的测试函数中，如下所示：

@pytest.mark.parametrize('data', [
    b'ab',
    b'xyz'*1000,
    b'12345'*1024**2,
    ... # etc
])
def test_compression(data):
    ... # compress the data
    ... # decompress the data
    assert decompressed_data == data

因为压缩大量数据需要很长时间，所以我想在一个失败后跳过所有剩余的测试。例如，如果输入b'ab'（第一个）测试失败，b'xyz'*1000并且b'12345'*1024**2应该跳过所有其他参数化（或 xfail 不被执行）。

我知道可以将标记附加到单个参数化，如下所示：

@pytest.mark.parametrize("test_input,expected", [
    ("3+5", 8),
    ("2+4", 6),
    pytest.param("6*9", 42, marks=pytest.mark.xfail),
])

但我不知道如何根据前一个测试用例的状态有条件地应用这些标记。有没有办法做到这一点？

标签： pythonunit-testingpytest

Answer 1

skipif标记是在执行测试之前评估的，因此无法通过依赖于其他测试结果的某种声明性标记（如）。不过，您可以在挂钩中应用自定义测试跳过逻辑。修改增量测试 -pytest文档中的测试步骤配方：

# conftest.py
import pytest

def pytest_sessionstart(session):
    session.failednames = set()

def pytest_runtest_makereport(item, call):
    if call.excinfo is not None:
        item.session.failednames.add(item.originalname)

def pytest_runtest_setup(item):
    if item.originalname in item.session.failednames:
        pytest.skip("previous test failed (%s)" % item.name)  # or use pytest.xfail like in the other answer

示例测试

@pytest.mark.parametrize('i', range(10))
def test_spam(i):
    assert i != 3

产量：

=================================== test session starts ===================================
collected 10 items

test_spam.py::test_spam[0] PASSED
test_spam.py::test_spam[1] PASSED
test_spam.py::test_spam[2] PASSED
test_spam.py::test_spam[3] FAILED
test_spam.py::test_spam[4] SKIPPED
test_spam.py::test_spam[5] SKIPPED
test_spam.py::test_spam[6] SKIPPED
test_spam.py::test_spam[7] SKIPPED
test_spam.py::test_spam[8] SKIPPED
test_spam.py::test_spam[9] SKIPPED

========================================= FAILURES ========================================
_______________________________________ test_spam[3] ______________________________________

i = 3

    @pytest.mark.parametrize('i', range(10))
    def test_spam(i):
>       assert i != 3
E       assert 3 != 3

test_spam.py:5: AssertionError
====================== 1 failed, 3 passed, 6 skipped in 0.06 seconds ======================

编辑：使用自定义标记

def pytest_runtest_makereport(item, call):
    markers = {marker.name for marker in item.iter_markers()}
    if call.excinfo is not None and 'skiprest' in markers:
        item.session.failednames.add(item.originalname)

def pytest_runtest_setup(item):
    markers = {marker.name for marker in item.iter_markers()}
    if item.originalname in item.session.failednames and 'skiprest' in markers:
        pytest.skip(item.name)

用法：

@pytest.mark.skiprest
@pytest.mark.parametrize('somearg', ['a', 'b', 'c'])
def test_marked(somearg):
    ...