I have a use case where I may use fixture multiple times inside a test in a "context manager" way. See example code below:
in conftest.py
class SomeYield(object):
def __enter__(self):
log.info("SomeYield.__enter__")
def __exit__(self, exc_type, exc_val, exc_tb):
log.info("SomeYield.__exit__")
def generate_name():
name = "{current_time}-{uuid}".format(
current_time=datetime.now().strftime("%Y-%m-%d-%H-%M-%S"),
uuid=str(uuid.uuid4())[:4]
)
return name
#pytest.yield_fixture
def some_yield():
name = generate_name()
log.info("Start: {}".format(name))
yield SomeYield()
log.info("End: {}".format(name))
in test_some_yield.py
def test_some_yield(some_yield):
with some_yield:
pass
with some_yield:
pass
Console output:
INFO:conftest:Start: 2017-12-06-01-50-32-5213
INFO:conftest:SomeYield.__enter__
INFO:conftest:SomeYield.__exit__
INFO:conftest:SomeYield.__enter__
INFO:conftest:SomeYield.__exit__
INFO:conftest:End: 2017-12-06-01-50-32-5213
Questions:
If I have some setup code in SomeYield.enter and cleanup code in
SomeYield.exit, is this the right way to do it using fixture for
multiple calls in my test?
Why didn't I see three occurrences of
enter and exit? Is this expected?
Related
I'm using pytest for testing with mixer library for generating model data. So, now I'm trying to setup my tests once before they run. I grouped them into TestClasses, set to my fixtures 'class' scope, but this doesn't work for me.
#pytest.mark.django_db
class TestCreateTagModel:
#classmethod
#pytest.fixture(autouse=True, scope='class')
def _set_up(cls, create_model_instance, tag_model, create_fake_instance):
cls.model = tag_model
cls.tag = create_model_instance(cls.model)
cls.fake_instance = create_fake_instance(cls.model)
print('setup')
def test_create_tag(self, tag_model, create_model_instance, check_instance_exist):
tag = create_model_instance(tag_model)
assert check_instance_exist(tag_model, tag.id)
conftest.py
pytest.fixture(scope='class')
#pytest.mark.django_db(transaction=True)
def create_model_instance():
instance = None
def wrapper(model, **fields):
nonlocal instance
if not fields:
instance = mixer.blend(model)
else:
instance = mixer.blend(model, **fields)
return instance
yield wrapper
if instance:
instance.delete()
#pytest.fixture(scope='class')
#pytest.mark.django_db(transaction=True)
def create_fake_instance(create_related_fields):
"""
Function for creating fake instance of model(fake means that this instance doesn't exists in DB)
Args:
related (bool, optional): Flag which indicates create related objects or not. Defaults to False.
"""
instance = None
def wrapper(model, related=False, **fields):
with mixer.ctx(commit=False):
instance = mixer.blend(model, **fields)
if related:
create_related_fields(instance, **fields)
return instance
yield wrapper
if instance:
instance.delete()
#pytest.fixture(scope='class')
#pytest.mark.django_db(transaction=True)
def create_related_fields():
django_rel_types = ['ForeignKey']
def wrapper(instance, **fields):
for f in instance._meta.get_fields():
if type(f).__name__ in django_rel_types:
rel_instance = mixer.blend(f.related_model)
setattr(instance, f.name, rel_instance)
return wrapper
But I'm catching exception in mixer gen_value method: Database access not allowed, use django_db mark(that I'm already use). Do you have any ideas how this can be implemented?
You can set things up once before a run by returning the results of the setup, rather than modifying the testing class directly. From my own attempts, it seems any changes to the class made within class-scope fixtures are lost when individual tests are run. So here's how you should be able to do this. Replace your _setup fixture with these:
#pytest.fixture(scope='class')
def model_instance(self, tag_model, create_model_instance):
return create_model_instance(tag_model)
#pytest.fixture(scope='class')
def fake_instance(self, tag_model, create_fake_instance):
return create_fake_instance(tag_model)
And then these can be accessed through:
def test_something(self, model_instance, fake_instance):
# Check that model_instance and fake_instance are as expected
I'm not familiar with Django myself though, so there might be something else with it going on. This should at least help you solve one half of the problem, if not the other.
I use testinfra with ansible transport. It provides host fixture which has ansible, so I can do host.ansible.get_variables().
Now I need to create a parametrization of test based on value from this inventory.
Inventory:
foo:
hosts:
foo1:
somedata:
- data1
- data2
I want to write a test which tests each of 'data' from somedata for each host in inventory. 'Each host' part is handled by testnfra, but I'm struggling with parametrization of the test:
#pytest.fixture
def somedata(host):
return host.ansible.get_variables()["somedata"]
#pytest.fixture(params=somedata):
def data(request):
return request.param
def test_data(host, data):
assert 'data' in data
I've tried both ways:
#pytest.fixture(params=somedata) -> TypeError: 'function' object is not iterable
#pytest.fixture(params=somedata()) -> Fixture "somedata" called directly. Fixtures are not meant to be called directly...
How can I do this? I understand that I can't change the number of tests at test time, but I pretty sure I have the same inventory at collection time, so, theoretically, it can be doable...
After reading a lot of source code I have came to conclusion, that it's impossible to call fixtures at collection time. There are no fixtures at collection time, and any parametrization should happen before any tests are called. Moreover, it's impossible to change number of tests at test time (so no fixture could change that).
Answering my own question on using Ansible inventory to parametrize a test function: It's possible, but it requires manually reading inventory, hosts, etc. There is a special hook for that: pytest_generate_tests (it's a function, not a fixture).
My current code to get any test parametrized by host_interface fixture is:
def cartesian(hosts, ar):
for host in hosts:
for interface in ar.get_variables(host).get("interfaces",[]):
yield (host, interface)
def pytest_generate_tests(metafunc):
if 'host_interface' in metafunc.fixturenames:
inventory_file = metafunc.config.getoption('ansible_inventory')
ansible_config = testinfra.utils.ansible_runner.get_ansible_config()
inventory = testinfra.utils.ansible_runner.get_ansible_inventory(ansible_config, inventory_file)
ar = testinfra.utils.ansible_runner.AnsibleRunner(inventory_file)
hosts = ar.get_hosts(metafunc.config.option.hosts)
metafunc.parametrize("host_interface", cartesian(hosts, ar))
You should use helper function instead of fixture to parametrize another fixture. Fixtures can not be used as decorator parameters in pytest.
def somedata(host):
return host.ansible.get_variables()["somedata"]
#pytest.fixture(params=somedata()):
def data(request):
return request.param
def test_data(host, data):
assert 'data' in data
This assumes that the host is not a fixture.
If the host is a fixture, there is hacky way to get around the problem. You should write the parameters to a tmp file or in a environment variable and read it with a helper function.
import os
#pytest.fixture(autouse=True)
def somedata(host):
os.environ["host_param"] = host.ansible.get_variables()["somedata"]
def get_params():
return os.environ["host_param"] # do some clean up to return a list instead of a string
#pytest.fixture(params=get_params()):
def data(request):
return request.param
def test_data(host, data):
assert 'data' in data
In my test suite, I have certain data-generation fixtures which are used with many parameterized tests. Some of these tests would want these fixtures to run only once per session, while others need them to run every function. For example, I may have a fixture similar to:
#pytest.fixture
def get_random_person():
return random.choice(list_of_people)
and 2 parameterized tests, one which wants to use the same person for each test condition and one which wants a new person each time. Is there any way for this fixture to have scope="session" for one test and scope="function" for another?
James' answer is okay, but it doesn't help if you yield from your fixture code. This is a better way to do it:
# Built In
from contextlib import contextmanager
# 3rd Party
import pytest
#pytest.fixture(session='session')
def fixture_session_fruit():
"""Showing how fixtures can still be passed to the different scopes.
If it is `session` scoped then it can be used by all the different scopes;
otherwise, it must be the same scope or higher than the one it is used on.
If this was `module` scoped then this fixture could NOT be used on `fixture_session_scope`.
"""
return "apple"
#contextmanager
def _context_for_fixture(val_to_yield_after_setup):
# Rather long and complicated fixture implementation here
print('SETUP: Running before the test')
yield val_to_yield_after_setup # Let the test code run
print('TEARDOWN: Running after the test')
#pytest.fixture(session='function')
def fixture_function_scope(fixture_session_fruit):
with _context_for_fixture(fixture_session_fruit) as result:
yield result
#pytest.fixture(scope='class')
def fixture_class_scope(fixture_session_fruit):
with _context_for_fixture(fixture_session_fruit) as result:
yield result
#pytest.fixture(scope='module')
def fixture_module_scope(fixture_session_fruit):
with _context_for_fixture(fixture_session_fruit) as result:
yield result
#pytest.fixture(scope='session')
def fixture_session_scope(fixture_session_fruit):
with _context_for_fixture(fixture_session_fruit) as result:
# NOTE if the `_context_for_fixture` just did `yield` without any value,
# there should still be a `yield` here to keep the fixture
# inside the context till it is done. Just remove the ` result` part.
yield result
This way you can still handle contextual fixtures.
Github issue for reference: https://github.com/pytest-dev/pytest/issues/3425
One way to do this to separate out the implementation and then have 2 differently-scoped fixtures return it. So something like:
def _random_person():
return random.choice(list_of_people)
#pytest.fixture(scope='function')
def get_random_person_function_scope():
return _random_person()
#pytest.fixture(scope='session')
def get_random_person_session_scope():
return _random_person()
I've been doing this:
def _some_fixture(a_dependency_fixture):
def __some_fixture(x):
return x
yield __some_fixture
some_temp_fixture = pytest.fixture(_some_fixture, scope="function")
some_module_fixture = pytest.fixture(_some_fixture, scope="module")
some_session_fixture = pytest.fixture(_some_fixture, scope="session")
Less verbose than using a context manager.
Actually there is a workaround for this using the request object.
You could do something like:
#pytest.fixture(scope='class')
def get_random_person(request):
request.scope = getattr(request.cls, 'scope', request.scope)
return random.choice(list_of_people)
Then back at the test class:
#pytest.mark.usefixtures('get_random_person')
class TestSomething:
scope = 'function'
def a_random_test():
def another_test():
However, this only works properly for choosing between 'function' and 'class' scope and particularly if the fixture starts as class-scoped (and then changes to 'function' or is left as is).
If I try the other way around (from 'function' to 'class') funny stuff happen and I still can't figure out why.
I'm running a ScalaTest (FlatSpec) suite programmatically, like so:
new MyAwesomeSpec().execute()
Is there some way I can figure out if all tests passed? Suite#execute() returns Unit here, so does not help. Ideally, I'd like to run the whole suite and then get a return value indicating whether any tests failed; an alternative would be to fail/return immediately on any failed test.
I can probably achieve this by writing a new FlatSpec subclass that overrides the Scalatest Suite#execute() method to return a value, but is there a better way to do what I want here?
org.scalatest.Suite also has run function, which returns the status of a single executed test.
With a few tweaking, we can access the execution results of each test. To run a test, we need to provide a Reporter instance. An ad-hoc empty reporter will be enough in our simple case:
val reporter = new Reporter() {
override def apply(e: Event) = {}
}
So, let's execute them:
import org.scalatest.events.Event
import org.scalatest.{Args, Reporter}
val testSuite = new MyAwesomeSpec()
val testNames = testSuite.testNames
testNames.foreach(test => {
val result = testSuite.run(Some(test), Args(reporter))
val status = if (result.succeeds()) "OK" else "FAILURE!"
println(s"Test: '$test'\n\tStatus=$status")
})
This will produce output similar to following:
Test: 'This test should pass'
Status=OK
Test: 'Another test should fail'
Status=FAILURE!
Having access to each test case name and its respective execution result, you should have enough data to achieve your goal.
I would like to narrow the scope of the pytest xfail mark. As I currently use it, it marks the entire test function, and any failure in the function is cool.
I would like to narrow that down to a smaller scope, perhaps with a context manager similar to "with pytest.raises (module.Error)". For example:
#pytest.mark.xfail
def test_12345():
first_step()
second_step()
third_step()
This test will xfail if I assert in any of the three methods I call. I would like instead for the test to xfail only if it asserts in second_step(), and not elsewhere. Something like this:
def test_12345():
first_step()
with pytest.something.xfail:
second_step()
third_step()
Is this possible with py.test?
Thanks.
You can define a context manager yourself that does it, like this:
import pytest
class XFailContext:
def __enter__(self):
pass
def __exit__(self, type, val, traceback):
if type is not None:
pytest.xfail(str(val))
xfail = XFailContext()
def step1():
pass
def step2():
0/0
def step3():
pass
def test_hello():
step1()
with xfail:
step2()
step3()
Of course you can also modify the contextmanager to look for specific exceptions.
The only caveat is that you cannot cause an "xpass" outcome, i.e. a special result that the (part of the) test unexpectedly passed.