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.
Related
Is there any benefit to using partially applied functions vs injecting dependencies into a class? Both approaches as I understand them shown here:
class DB(conn: String) {
def get(sql: String): List[Any] = _
}
object DB {
def get(conn: String) (sql: String): List[Any] = _
}
object MyApp {
val conn = "jdbc:..."
val sql = "select * from employees"
val db1 = new DB(conn)
db1.get(sql)
val db2 = DB.get(conn) _
db2(sql)
}
Using partially-applied functions is somewhat simpler, but the conn is passed to the function each time, and could have a different conn each time it is called. The advantage of using a class is that it can perform one-off operations when it is created, such as validation or caching, and retain the results in the class for re-use.
For example the conn in this code is a String but this is presumably used to connect to a database of some sort. With the partially-applied function it must make this connection each time. With a class the connection can be made when the class is created and just re-used for each query. The class version can also prevent the class being created unless the conn is valid.
The class is usually used when the dependency is longer-lived or used by multiple functions. Partial application is more common when the dependency is shorter-lived, like during a single loop or callback. For example:
list.map(f(context))
def f(context: Context)(element: Int): Result = ???
It wouldn't really make sense to create a class just to hold f. On the other hand, if you have 5 functions that all take context, you should probably just put those into a class. In your example, get is unlikely to be the only thing that requires the conn, so a class makes more sense.
I'm unsure if this is possible but I was wondering if there is a way to get a variable from an outer scope without passing it as an argument.
I've played around with global() and inspect but i'm having issues trying to get the attribute.
Here's what i'm trying to do:
class Example:
#staticmethod
def query(**kwargs):
print(f.read())
with open(__file__) as f:
Example.query(foo='bar')
So after a while of back and forth I have finally found a solution to my issue.
As Matthias suggested I use global to find the object, i decided to use inspect to add it myself like so:
Assigning
def __enter__(self):
inspect.stack()[1][0].f_globals["_ExampleName"] = self
Retrieving (Fixed)
#staticmethod
def _find_example():
stack = inspect.stack()
for stack_index in range(2, len(stack)):
stack_globals = inspect.stack()[stack_index][0].f_globals
if "_ExampleName" in stack_globals.keys():
return stack_globals["_ExampleName"]
This is a bit 'dodgy' as inspect is not ment to be used in a production environment, However works and solves my issue
Here is a MCVE of what you're trying to do.
class Example:
#staticmethod
def query(**kwargs):
print(f.read())
with open(__file__) as f:
Example.query(foo='bar')
Works as expected.
What you should do is have the Client class set a class variable to the current session.
class Client:
last_session = None
def Session():
# code that creates new session, in variable s
Client.last_session = s
return s
client = Client()
with client.Session as s:
Example.query(foo=bar)
Class Example:
#staticmethod
def query(**kwargs):
s = Client.last_session
s.magic_stuff()
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 have some code that requires an Environment Variable to run correctly. But when I run my unit tests, it bombs out once it reaches that point unless I specifically export the variable in the terminal. I am using Scala and sbt. My code does something like this:
class something() {
val envVar = sys.env("ENVIRONMENT_VARIABLE")
println(envVar)
}
How can I mock this in my unit tests so that whenever sys.env("ENVIRONMENT_VARIABLE") is called, it returns a string or something like that?
If you can't wrap existing code, you can change UnmodifiableMap System.getenv() for tests.
def setEnv(key: String, value: String) = {
val field = System.getenv().getClass.getDeclaredField("m")
field.setAccessible(true)
val map = field.get(System.getenv()).asInstanceOf[java.util.Map[java.lang.String, java.lang.String]]
map.put(key, value)
}
setEnv("ENVIRONMENT_VARIABLE", "TEST_VALUE1")
If you need to test console output, you may use separate PrintStream.
You can also implement your own PrintStream.
val baos = new java.io.ByteArrayOutputStream
val ps = new java.io.PrintStream(baos)
Console.withOut(ps)(
// your test code
println(sys.env("ENVIRONMENT_VARIABLE"))
)
// Get output and verify
val output: String = baos.toString(StandardCharsets.UTF_8.toString)
println("Test Output: [%s]".format(output))
assert(output.contains("TEST_VALUE1"))
Ideally, environment access should be rewritten to retrieve the data in a safe manner. Either with a default value ...
scala> scala.util.Properties.envOrElse("SESSION", "unknown")
res70: String = Lubuntu
scala> scala.util.Properties.envOrElse("SECTION", "unknown")
res71: String = unknown
... or as an option ...
scala> scala.util.Properties.envOrNone("SESSION")
res72: Option[String] = Some(Lubuntu)
scala> scala.util.Properties.envOrNone("SECTION")
res73: Option[String] = None
... or both [see envOrSome()].
I don't know of any way to make it look like any/all random env vars are set without actually setting them before running your tests.
You shouldn't test it in unit-test.
Just extract it out
class F(val param: String) {
...
}
In your prod code you do
new Foo(sys.env("ENVIRONMENT_VARIABLE"))
I would encapsulate the configuration in a contraption which does not expose the implementation, maybe a class ConfigValue
I would put the implementation in a class ConfigValueInEnvVar extends ConfigValue
This allows me to test the code that relies on the ConfigValue without having to set or clear environment variables.
It also allows me to test the base implementation of storing a value in an environment variable as a separate feature.
It also allows me to store the configuration in a database, a file or anything else, without changing my business logic.
I select implementation in the application layer.
I put the environment variable logic in a supporting domain.
I put the business logic and the traits/interfaces in the core domain.