[英]using fixture return value as value in mark.parametrize()
my question is - is it possible to use return value from fixture as a value in parametrize? 我的问题是 - 是否可以使用fixture中的返回值作为参数化中的值? The problem is - I'd like to dynamically get possible values (for example, available systems on a virtual server) for parametrize. 问题是 - 我想动态获取参数化的可能值(例如,虚拟服务器上的可用系统)。 I can access these when a virtual server is created by one of the fixtures. 当其中一个灯具创建虚拟服务器时,我可以访问这些。 Tests look like this (pseudo-code-ish): 测试看起来像这样(伪代码):
[conftest.py]
@pytest_fixture(scope='session')
def test_server(request):
test_server = Server([default_params])
test_server.add()
def fin():
test_server.delete()
request_addfinalizer(fin)
return test_server()
[tests.py]
def test_basic_server(test_server):
systems = test.server.get_available_systems()
for system in systems:
test_server.install(system)
test_server.run_checks()
test_server.uninstall(system)
def test_other(test_server):
[other tests]
etc
This way, one server is added for each session, then all tests run on it, and after session ends, server is removed. 这样,为每个会话添加一个服务器,然后在其上运行所有测试,并在会话结束后删除服务器。 But is there a way to get the available systems in @pytest.mark.parametrize without explicitly listing them (statically as a list in parametrize), using the method from server that is added when the session begins? 但有没有办法在@ pytest.mark.parametrize中获取可用的系统而不显式列出它们(静态地作为参数化中的列表),使用会话开始时添加的服务器中的方法? That way each system would run in a separate test. 这样每个系统都可以在单独的测试中运行。
I tried using test_server in another fixture and then returning the list (the same way test_server is returned by test_server fixture, but I cannot use that as a value in parametrize - since decorator is evaluated before the test_server fixture is called in any test, and getting the list depends on test_server fixture. 我尝试在另一个fixture中使用test_server然后返回列表(test_server fixture返回test_server的方式相同,但是我不能将它用作参数化中的值 - 因为在任何测试中调用test_server fixture之前评估decorator,并获得该列表取决于test_server fixture。
This would be ideal: 这将是理想的:
[tests.py]
@pytest.mark.parametrize('system',[systems_list <- dynamically generated
when the server is created])
def test_basic_server(test_server,system):
test_server.install(system)
test_server.run_checks()
test_server.uninstall(system)
This is just a very basic example, in my tests I need to parametrize based on multiple scenarios and values and I end up with giant arrays when I do it statically. 这只是一个非常基本的例子,在我的测试中,我需要根据多个场景和值进行参数化,当我静态执行时,我最终会得到巨型数组。
But the principle remains the same - basically: can I call the fixture before the first test using this fixture runs, or how can pytest.mark.parametrize() access fixture values? 但原理保持不变 - 基本上:我可以在使用此夹具运行的第一次测试之前调用夹具,或者pytest.mark.parametrize()如何访问夹具值?
I think you may be unable to achieve what you want directly. 我想你可能无法直接达到你想要的效果。 Because @pytest.mark.parametrize
is being called during collecting, and fixtures will be called after collection completed. 因为在收集过程中会调用@pytest.mark.parametrize
,并且在收集完成后将调用fixture。
But I have an alternative way to achieve similar result, mainly by extending pytest plugin pytest_generate_tests
and using method metafunc.parametrize
. 但是我有一个替代的方式来达到同样的效果,主要是通过扩展插件pytest pytest_generate_tests
和使用方法metafunc.parametrize
。 https://pytest.org/latest/parametrize.html#basic-pytest-generate-tests-example https://pytest.org/latest/parametrize.html#basic-pytest-generate-tests-example
Here is my solution. 这是我的解决方案。 In conftest.py 在conftest.py中
class System(object):
def __init__(self, name):
self.name = name
def __repr__(self):
return "<System '{}'>".format(self.name)
def get_available_systems():
return [System('A'), System('B'), System('C')]
def pytest_generate_tests(metafunc):
if 'system' in metafunc.fixturenames:
available_systems = get_available_systems()
metafunc.parametrize('system', available_systems)
In test file: 在测试文件中:
def test_basic_server(system):
print(system)
This is the output, you will have access to each system in test. 这是输出,您将可以访问测试中的每个系统。
collected 3 items
test_01.py::test_basic_server[system0] <System 'A'>
PASSED
test_01.py::test_basic_server[system1] <System 'B'>
PASSED
test_01.py::test_basic_server[system2] <System 'C'>
PASSED
The bad thing is, get_available_systems
will be called every time whenever using fixture system
, which is not what you want. 不好的是,每次使用夹具system
时都会调用get_available_systems
,这不是你想要的。 But I think it's not hard to add some extra logic to make the query logic only be executed once. 但我认为添加一些额外的逻辑以使查询逻辑只执行一次并不困难。
For example: 例如:
def pytest_generate_tests(metafunc):
if 'system' in metafunc.fixturenames:
if hasattr(metafunc.config, 'available_systems'):
available_systems = metafunc.config.available_systems
else:
available_systems = get_available_systems()
metafunc.config.available_systems = available_systems
metafunc.parametrize('system', available_systems)
I was able to work a similar problem where I have to generate tests data that is to be used for parameterization on the fly: 我能够处理类似的问题,我必须生成用于即时参数化的测试数据:
class TestFilters(object):
cls_testdata1 = []
def setup_class(cls):
r = []
for i in range(5):
r.append((x, y, z))
TestFilters.cls_testdata1 = r
@pytest.mark.parametrize("filter_id", list(range(5)))
def test_func(self, filter_id):
params = TestFilters.cls_testdata1[filter_id]
... ...
This would support adding the parameters dynamically, only that you need to predetermine the number of tests. 这将支持动态添加参数,只需要预先确定测试次数。
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