I have a UserRepository class that I am writing unittests for
class UserRepository(object):
"""
Repository that handles storage and retrieval of models.User objects
in and from the datastore.
"""
def create(self, user):
"""
Create the given user in the datastore if it doesn't exist yet.
Args:
user: The user to create.
Returns:
The created user.
Raises:
exc.DuplicateEntity: If the desired phonenumber is
already taken.
"""
duplicate_user = models.User.query(models.User.phonenumber == user.phonenumber).fetch()
if duplicate_user:
raise exc.DuplicateEntity()
user.put()
return user
I have these tests for it
class UserServiceTest(unittest.TestCase):
"""Tests for the UserService."""
def setUp(self):
"""
Called before tests are run.
"""
self.user_repo = repositories.UserRepository()
#self.policy = datastore_stub_util.PseudoRandomHRConsistencyPolicy(probability=1)
def test_create(self):
"""
Test if the create method creates a user.
"""
ndb.delete_multi(models.User.query().fetch(keys_only=True))
user = models.User(phonenumber='+31612345678#',
email='[email protected]',
password='1234abcd')
ret_user = self.user_repo.create(user)
self.assertEqual(ret_user, user)
def test_create_duplicate_fails(self):
"""
Test if attempting to create a user with an existing phonenumber
fails.
"""
ndb.delete_multi(models.User.query().fetch(keys_only=True))
user = models.User(phonenumber='+31612345678#',
email='[email protected]',
password='1234abcd')
self.user_repo.create(user)
with self.assertRaises(exc.DuplicateEntity):
self.user_repo.create(user)
The ndb.delete_multi(models.User.query().fetch(keys_only=True)) is to clear existing users from the test environment so test cases don't have influence on one another.
This is the custom exception
class DuplicateEntity(Exception):
"""Exception to raise when trying to create a duplicate entity."""
I run the tests with
$ nosetests --with-gae
It outputs
======================================================================
FAIL: Test if attempting to create a user with an existing phonenumber
----------------------------------------------------------------------
Traceback (most recent call last):
File "/tests/dal/test_repositories.py", line 53, in test_create_duplicate_fails
self.user_repo.create(user)
AssertionError: DuplicateEntity not raised
----------------------------------------------------------------------
Ran 2 tests in 0.080s
FAILED (failures=1)
Which is unexpected, because the 2nd call to .create here should raise the exception since there already is a user with that phonenumber.
I'm sure the code works, because I've tested it live.
What's also weird is that if I add a call to .create above the with statement, it does raise the exception:
self.user_repo.create(user)
self.user_repo.create(user)
with self.assertRaises(exc.DuplicateEntity):
self.user_repo.create(user)
So it's raised on the 3rd call, but not the 2nd.
I have a feeling it's related to the datastore consistency policy, as documented here:
The PseudoRandomHRConsistencyPolicy class lets you control the likelihood of a write applying before each global (non-ancestor) query. By setting the probability to 0%, we are instructing the datastore stub to operate with the maximum amount of eventual consistency. Maximum eventual consistency means writes will commit but always fail to apply, so global (non-ancestor) queries will consistently fail to see changes.
however I don't know how nosegae handles this. Is it even configurable? nosegae doesn't have alot of documentation.
How can I work around (or fix) this?
Your problem is you are using a query to test for duplicates and that isn't guaranteed to work due to eventual consistency. You will note that the tests in the document you referred to all use ancestor queries which do guarantee consistency.
My take is this, it is expected and correct behavior (the AssertionError: DuplicateEntity not raised error) and highlights a problem with you model/approach.