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Python set self-variables by other class using cls?

I wonder if it is possible to set variables of a class by a different class using cls?
The story behind it:
I'm writing tests for different purposes but see that one part of the setup is the same as in an already existing class. So I would do the setUp by the already existing one:
The original code:
class TestBase(unittest.TestCase):
def setUp(self):
self.handler = txt.getHandler(hcu.handler3())
self.curves = self.handler.curves()
self.arguments = (getInit())
self.ac = self.connect2DB(self.arguments)
self.au = AutoUtils()
This has worked well so far.
Now in my TestClient I'd like to make use of that:
from .testsDB import TestBase as tb
class TestClient(unittest.TestCase):
def setUp(self):
tb.setUp()
And modified in the TestBase the setUp to the following:
#classmethod
def setUp(cls):
cls.handler = txt.getHandler(hcu.handler3())
cls.graph = cls.handler.curves()
cls.argv = (getInit())
cls.ac = cls.connect2DB(cls.arguments)
cls.au = AutoUtils()
But I'm getting an error as soon as I use one of the values defined in the variables of the TestClient-class:
def test_Duplicates(self):
self.testDB = self.ac.connect(self.ac.client, self.arguments[4])
With the error:
In test_Duplicate (Curves.tests_client.TestClient) :
Traceback (most recent call last):
File "/home/qohelet/Curves/tests_client.py", line 49, in test_Duplicate
self.testDB = self.ac.connect(self.ac.client, self.arguments[4])
AttributeError: 'TestClient' object has no attribute 'ac'
Is it actually possible what I'm trying?
EDIT:
After writing this and seeing the answers I did another review. Yes indeed there is a circular issue I'm having.
TestBase has the function connect2DB which will be executed on setUp.
If it refers to itself (as in the original) it's fine.
If I replace the self with cls it will try to execute TestClient.connect2DB in the setUp - which does not exist. So it would require self again as putting connect2DB into TestClient is not an option.
How to solve that?

Surely your new class should just inherit the setup()?
from .testsDB import TestBase as tb
class TestClient(tb):
def test_Duplicates(self):
self.testDB = self.ac.connect(self.ac.client, self.arguments[4])
The whole point of inheritance is that you don't modify what you inherit from. Your new class should just make use of what is supplied. That is why inheritance is sometimes called programming by difference.

Python mock a method when specific argument

I have a python method like
import external_object
from external_lib1 import ExternalClass1
from external_lib2 import Hook
class MyClass(self):
def my_method(self):
ExternalClass.get('arg1') #should be mocked and return a specific value with this arg1
ExternalClass.get('arg2') #should be mocked and return a specific value with this arg2
def get_hook(self):
return Hook() # return a mock object with mocked method on it
def my_method(self):
object_1 = external_object.instance_type_1('args') # those are two different object instanciate from the same lib.
object_2 = external_object.instance_type_2('args')
object_1.method_1('arg') # should return what I want when object_1 mocked
object_2.method_2 ('arg') # should return what I want when object_2 mocked
In my test I would like to realise what I put in comments.
I could manage to do it, but every time it gets really messy.
I use to call flexmock for some stuff (by example ExternalClass.get('arg1') would be mock with a flexmock(ExternalClass).should_return('arg').with_args('arg') # etc...) but I'm tired of using different test libs to mock.
I would like to use only the mock library but I struggle to find a consistent way of doing it.

I like to use python's unittest lib. Concretely the unittest.mock which is a great lib to customize side effects and return value in unit tested functions.
They can be used as follows:
class Some(object):
"""
You want to test this class
external_lib is an external component we cannot test
"""
def __init__(self, external_lib):
self.lib = external_lib
def create_index(self, unique_index):
"""
Create an index.
"""
try:
self.lib.create(index=unique_index) # mock this
return True
except MyException as e:
self.logger.error(e.__dict__, color="red")
return False
class MockLib():
pass
class TestSome(unittest.TestCase):
def setUp(self):
self.lib = MockLib()
self.some = Some(self.lib)
def test_create_index(self):
# This will test the method returns True if everything went fine
self.some.create_index = MagicMock(return_value={})
self.assertTrue(self.some.create_index("test-index"))
def test_create_index_fail(self):
# This will test the exception is handled and return False
self.some.create_index = MagicMock(side_effect=MyException("error create"))
self.assertFalse(self.some.create_index("test-index"))
Put the TestSome() class file somewhere like your-codebase-path/tests and run:
python -m unittest -v
I hope it's useful.

Subclassing TestCase in Python: Overwriting Field in Parent TestCase

I'm writing integration tests for an Alexa app.
Our application uses a controller-request-response pattern. The controller receives a request with a specified intent and session variables, routes the request to functions that do some computation with the session variables, and returns a response object with the results of that computation.
We get the right behavior from UnhandledIntentTestCase as far as test_for_smoke is concerned. However, test_returning_reprompt_text
never fires, because returns_reprompt_text is never overwritten.
Can someone explain how I can overwrite it in the parent class and/or
how the correct intent name is passed to the request object in setUpClass?
intent_base_case.py
import unittest
import mycity.intents.intent_constants as intent_constants
import mycity.mycity_controller as mcc
import mycity.mycity_request_data_model as req
import mycity.test.test_constants as test_constants
###############################################################################
# TestCase parent class for all intent TestCases, which are integration tests #
# to see if any changes in codebase have broken response-request model. #
# #
# NOTE: Assumes that address has already been set. #
###############################################################################
class IntentBaseCase(unittest.TestCase):
__test__ = False
intent_to_test = None
returns_reprompt_text = False
#classmethod
def setUpClass(cls):
cls.controller = mcc.MyCityController()
cls.request = req.MyCityRequestDataModel()
key = intent_constants.CURRENT_ADDRESS_KEY
cls.request._session_attributes[key] = "46 Everdean St"
cls.request.intent_name = cls.intent_to_test
cls.response = cls.controller.on_intent(cls.request)
#classmethod
def tearDownClass(cls):
cls.controller = None
cls.request = None
def test_for_smoke(self):
self.assertNotIn("Uh oh", self.response.output_speech)
self.assertNotIn("Error", self.response.output_speech)
def test_correct_intent_card_title(self):
self.assertEqual(self.intent_to_test, self.response.card_title)
#unittest.skipIf(not returns_reprompt_text,
"{} shouldn't return a reprompt text".format(intent_to_test))
def test_returning_reprompt_text(self):
self.assertIsNotNone(self.response.reprompt_text)
#unittest.skipIf(returns_reprompt_text,
"{} should return a reprompt text".format(intent_to_test))
def test_returning_no_reprompt_text(self):
self.assertIsNone(self.response.reprompt_text)
test_unhandled_intent.py
import mycity.test.intent_base_case as base_case
########################################
# TestCase class for unhandled intents #
########################################
class UnhandledIntentTestCase(base_case.IntentBaseCase):
__test__ = True
intent_to_test = "UnhandledIntent"
returns_reprompt_text = True
output
======================================================================
FAIL: test_correct_intent_card_title (mycity.test.test_unhandled_intent.UnhandledIntentTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/wdrew/projects/alexa_311/my_city/mycity/mycity/test/intent_base_case.py", line 44, in test_correct_intent_card_title
self.assertEqual(self.intent_to_test, self.response.card_title)
AssertionError: 'UnhandledIntent' != 'Unhandled intent'
- UnhandledIntent
? ^
+ Unhandled intent
? ^^
======================================================================
FAIL: test_returning_no_reprompt_text (mycity.test.test_unhandled_intent.UnhandledIntentTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/wdrew/projects/alexa_311/my_city/mycity/mycity/test/intent_base_case.py", line 56, in test_returning_no_reprompt_text
self.assertIsNone(self.response.reprompt_text)
AssertionError: 'So, what can I help you with today?' is not None
----------------------------------------------------------------------

This is because of execution order. The SkipIf decorators are executed once during the parsing of the IntentBaseCase class. They aren't re-executed for each class or for each call to the test function.
The decorator pattern for SkipIf is designed for use with fixed global variables such as versions of dependent modules, operating system or some other external resource who's availability can be calculated or known in the global context.
Skipping tests is also something that should be done for external reasons, not for internal ones such as the needs of a sub-class. A skip is still a kind of failing test which is indicated in the report so you can see your test suite isn't exercising the whole of the functional scope of the project.
You should redesign your base class structure so functions are only available to run if the sub-class and skip using Skip for this. My recommendation would be:
class IntentBaseCase(unittest.TestCase):
...
class RepromptBaseCase(IntentBaseCase):
def test_returning_reprompt_text(self):
self.assertIsNotNone(self.response.reprompt_text)
class NoRepromptBaseCase(IntentBaseCase):
def test_returning_no_reprompt_text(self):
self.assertIsNone(self.response.reprompt_text)
You should also consider moving the response portion out of the setUp and put it into a test_ function of it's own and change these test_returning functions into a simpler assertReprompt and assertNoReprompt functions. It's a good idea to set up the tests in setUp, but not a good idea to run the actual code there.

Python Unittest and object initialization

My Python version is 3.5.1
I have a simple code (tests.py):
import unittest
class SimpleObject(object):
array = []
class SimpleTestCase(unittest.TestCase):
def test_first(self):
simple_object = SimpleObject()
simple_object.array.append(1)
self.assertEqual(len(simple_object.array), 1)
def test_second(self):
simple_object = SimpleObject()
simple_object.array.append(1)
self.assertEqual(len(simple_object.array), 1)
if __name__ == '__main__':
unittest.main()
If I run it with command 'python tests.py' I will get the results:
.F
======================================================================
FAIL: test_second (__main__.SimpleTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "tests.py", line 105, in test_second
self.assertEqual(len(simple_object.array), 1)
AssertionError: 2 != 1
----------------------------------------------------------------------
Ran 2 tests in 0.003s
FAILED (failures=1)
Why it is happening? And how to fix it. I expect that each tests run will be independent (each test should pass), but it is not as we can see.

The array is shared by all instances of the class. If you want the array to be unique to an instance you need to put it in the class initializer:
class SimpleObject(object):
def __init__(self):
self.array = []
For more information take a look at this question: class variables is shared across all instances in python?

This can also be accomplished directly in unittest if you prefer to use only 1 class. Implement the setUp class. setUp runs before any of the tests are run as the class is instantiated. It is similar to init but conforms to the unittest library. Note the opposite is tearDown which is executed at the end of the test class if you need to build and deprecate objects. Example:
class SimpleObject(unitest.TestCase):
def setUp(self):
# I run first
self.array = []
def some_test(self):
self.assertTrue(self.array == [])
<some test code here>
def tearDown(self):
# I run last
self.array = []. # or whatever teardown code you need
enjoy!

How can I access variables set in the Python nosetests setup function

I think what I'm trying to do is fairly simple. I want to initialize a couple of variables in a test setup function, and then use them in the test functions that are decorated with that setup. The following trivial example illustrates what I mean:
from nose.tools import *
def setup():
foo = 10
def teardown():
foo = None
#with_setup(setup, teardown)
def test_foo_value():
assert_equal(foo, 10)
This results in:
$ nosetests tests/test_foo.py
E
======================================================================
ERROR: test_foo.test_foo_value
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/mtozzi/.virtualenvs/foo/local/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
self.test(*self.arg)
File "/home/mtozzi/code/foo/tests/test_foo.py", line 12, in test_foo_value
assert_equal(foo, 10)
NameError: global name 'foo' is not defined
----------------------------------------------------------------------
Ran 1 test in 0.006s
FAILED (errors=1)
With the old unittest style, I could set these as instance variables on the test class, but I thought nosetests didn't require you to use classes. I've also considered setting them as package global variables, but that doesn't seem like a terribly good practice. I hope there's something obvious I'm missing for doing this.

As the comments to your question already suggested, simply switch to classes and use instance variables like self.foo. That's the way it should be done.
If you insist on not using classes, try global variables. You didn't hear this from me, though.
from nose.tools import *
foo = None
def setup():
global foo # Ugly.
foo = 10
def teardown():
global foo # Ugly.
foo = None
#with_setup(setup, teardown)
def test_foo_value():
assert_equal(foo, 10)
A third variant might be to use a dictionary for your values. This is slightly less ugly but horribly clumsy:
from nose.tools import *
_globals = {'foo': None}
def setup():
_globals['foo'] = 10
def teardown():
_globals['foo'] = None
#with_setup(setup, teardown)
def test_foo_value():
foo = _globals['foo']
assert_equal(foo, 10)

I use a custom with_setup decorator that uses the poor man's nonlocal: https://gist.github.com/garyvdm/392ae20c673c7ee58d76
def setup():
foo = 10
return [foo], {}
def teardown(foo):
pass
#with_setup_args(setup, teardown)
def test_foo_value(foo):
nose.tools.assert_equal(foo, 10)
For projects that are Python 3 only, I use nonlocal rather than .extend/.update for arguments, kwargs.