GAE Datastore Fixtures idea

fixtures.py

import datetime
from nosegae.fixture import NdbFixture
import models


class MyGreetings(NdbFixture):
  """Holds all data fixtures to be managed by the library
  
  Each inner class's attributes are used as `kwargs`
  in `model`'s constructor like similar to
  
  >>> for k, attrs in MyGreetings.inner_classes_as_dict()
  ...   entity = MyGreetings.model(**attrs)
  ...   MyGreetings.entities[k] = entity
  
  MyGreetings.entities is now a dict similar to:
  {'GreetingOne': Greeting(content="FIRST!", date=datetime.datetime(2015, 1, 1, 10, 30, 00)),
   'GreetingTwo': ...}
  """
  model = models.Greeting  # Model name for all data objects
  
  class GreetingOne(object):
    content = "FIRST!"
    date = datetime.datetime(2015, 1, 1, 10, 30, 00)
  
  class GreetingTwo(object):
    content = "I don't know how I ever lived without you!"
    date = datetime.datetime(2015, 1, 1, 16, 45, 00)
  
  class GreetingThree(object):
    content = "Hi guys, thanks for the site!"
    date = datetime.datetime(2015, 1, 2, 22, 00, 00)

greetinglib.py

import models


def greetings_since_date(start_date):
  """Gets a list of greetings since `start_date`
  
  Args
    :param datetime.datetime start_date: Filter for the oldest Greeting date
  Returns
    :return: A list of Greetings since the datetime given
    :rtype: list of Greeting
  """
  return list(models.Greeting.query(models.Greeting.date >= start_date))

models.py

from google.appengine.ext import ndb


class Greeting(ndb.Model):
  """Models an individual Guestbook entry with content and date."""
  content = ndb.StringProperty()
  date = ndb.DateTimeProperty()

tests.py

import datetime
import greetinglib
import fixtures
from nosegae.fixture import data

# data() creates the entities and passes them as `kwargs` into
# the wrapped function and then cleans them up after execution.
# similar to:
# >>> def data(func):
# ...   def wrapper(fixture):
# ...     fixture_instance = fixture()
# ...     wrapped(**fixture_instance.get_entities())
# ...     fixture_instance.cleanup()
# ...   return wrapper
@data(fixtures.MyGreetings)
def test_greetings_since_date(**entities):
  # entities is fixtures.MyGreetings.entities
  start_date = datetime.datetime(2015, 1, 1, 11, 00, 00)
  
  greetings = greetinglib.greetings_since_date(start_date)
  # assert the list of Greetings is the same length as all data fixtures that have
  # a date >= start_date
  assert len(greetings) == len([v for v in entities.values() if v.date >= start_date])