Pytest：参数化夹具返回路径或读取数据

Question

I have following test case:

@pytest.mark.parametrize('env_a, env_b', [(env_a, env_b)], indirect=True) #its existing fixture, cannot modify it
@pytest.mark.parametrize('platform_a, platform_b', [(platform_a, platform_b)])
@pytest.mark.parametrize('resource', [resource1, resource2, resource3, resource4])
def test_compare_items_lists(env_a, env_b, platform_a, platform_b, resource):

    path_a = env_a / platform_a / resource / file.txt #move to fixture
    path_b = env_b / platform_b / resource / file.txt #move to fixture

    list_of_items_in_a = path_a.read() #move to fixture
    list_of_items_in_b = path_b.read() #move to fixture

    extras_in_a = get_extras(list_of_items_in_a, list_of_items_in_b)
    extras_in_b = get_extras(list_of_items_in_b, list_of_items_in_a)

    assert not extras_in_a and not extras_in_b

This parameterized test do:

• path preparation
• data read
• data compare

but it's test, so should only compare data.

So I guess fixture(s?) should be created to prepare paths and read files. Then it should be passed to test which should only compare data. But how to do it?

Answer 1

pytest fixtures can be parametrized by setting the params option.

You can extract each marker to a separate fixture.

@pytest.fixture(params=[(platform_a, platform_b)], ids=['platform_a,platform_b'])
def platform(request):
    yield request.param

@pytest.fixture(params=[(env_a, env_b)], ids=['env_a,env_b'])
def env(request):
    yield request.param

@pytest.fixture(params=[resource1, resource2, resource3, resource4])
def resource(request):
    yield request.param

Then use them in another fixture that builds the resource path and returns the contents from it.

@pytest.fixture
def diffable_resources(request, env, platform, resource):
    env_a, env_b = env
    platform_a, platform_b = platform
    resource = resource

    path_a = env_a / platform_a / resource / 'file.txt'
    path_b = env_b / platform_b / resource / 'file.txt'
    yield (path_a.read(), path_b.read())

That way your test can be like:

def test_foo(diffable_resources):
    list_of_items_in_a, list_of_items_in_b = diffable_resources
    extras_in_a = get_extras(list_of_items_in_a, list_of_items_in_b)
    extras_in_b = get_extras(list_of_items_in_b, list_of_items_in_a)

    assert not extras_in_a and not extras_in_b