以编程方式在pytest插件中注册fixture(Programmaticly register a fixture in a pytest plugin)

 我正在寻找一种方法从Python运行一些pytest单元测试并动态注册pytest fixture。 正如Pytest文档中所解释的，当以编程方式运行测试时， 可以使用自定义插件更改其行为 。 我有以下设置 
 
 validation.py （包含要运行的测试） 
 
def test_valid(new_fixture):
    assert new_fixture > 0
 
 随着推出， 
 
import pytest

new_fixture_value = 36

class FixtureRegPlugin(object):
    def pytest_sessionstart(self):
        print('Test session start')

        @pytest.fixture
        def new_fixture():
            return new_fixture_value

pytest.main(['-sv', './validation.py'], plugins=[FixtureRegPlugin()])
 
 这里我们使用自定义插件在validation.py运行测试，该插件为pytest_sessionstart注册了一个钩子。 这个钩子在测试会话开始时执行，我可以按预期看到打印输出。 但是， new_fixture未注册，因此测试失败并显示“找不到夹具”错误。 
 
 目标是在运行时修改fixture的结果，因此我不能将其定义放在validation.py 。 

I am looking for a way run some pytest unit tests from Python and register a pytest fixture dynamically. As explained in in the Pytest documentation, when running tests programmatically their behaviour can be altered with a custom plugin. I have the following setup
 
validation.py (contains the tests to run)
 
def test_valid(new_fixture):
    assert new_fixture > 0
 
which is launched with,
 
import pytest

new_fixture_value = 36

class FixtureRegPlugin(object):
    def pytest_sessionstart(self):
        print('Test session start')

        @pytest.fixture
        def new_fixture():
            return new_fixture_value

pytest.main(['-sv', './validation.py'], plugins=[FixtureRegPlugin()])
 
here we run tests in validation.py with a custom plugin that registers a hook for pytest_sessionstart. This hook is executed at the begining of the test session, and I can see the printed output as expected. However, the new_fixture is not registered, and so the test fails with a "fixture not found" error.
 
The goal is to modify the result of the fixture at runtime and so I cannot just place its definition inside validation.py.

原文：https://stackoverflow.com/questions/46327646