FACTORYBOY Creating data for unit tests in an easy way @andreagrandi Andrea Grandi 

HOW TO GET DATA FOR UNIT TESTS • Using production DB – Do NOT do it! • Using fixtures – Not very handy • Using the ORM way to create data – It's ok but it can be long, repetitive and increase the lines of code in unittests • Or ... 

FACTORYBOY • Support for multiple build strategies (unsaved/saved instances: build() and create() ) • Powerful helpers for common cases (sequences, sub-factories, reverse dependencies, circular factories, ...) • Support for various ORMs (currently Django, Mogo, MongoEngine, SQLAlchemy) • Python >= 2.6 and PyPy are supported 

FACTORYBOY: DEFINING FACTORIES • subclass factory.Factory • add a class Meta block • set the model attribute of the Meta block • add default values 

FACTORYBOY: DEFINING FACTORIES (EXAMPLE) import factory from . import models class CustomerFactory(factory.Factory): class Meta: model = models.Customer first_name = 'John' last_name = 'Doe' admin = False 

FACTORYBOY: USING FACTORIES # Returns a Customer instance that's not saved customer = CustomerFactory.build() # Returns a saved Customer instance customer = CustomerFactory.create() # Returns a dict of attributes that can be used to # build a Customer instance attributes = CustomerFactory.attributes() 

YOU CAN ALWAYS OVERRIDE # Build a Customer instance and override first_name >>> customer = CustomerFactory.build(first_name='Joe') >>> customer.first_name "Joe" 

Lazy Attributes class CustomerFactory(factory.Factory): class Meta: model = models.Customer first_name = 'Joe' last_name = 'Blow' email = factory.LazyAttribute( lambda a:'{0}.{1}@example.com'.format( a.first_name, a.last_name).lower()) 

Sequences class CustomerFactory(factory.Factory): class Meta: model = models.Customer email = factory.Sequence( lambda n: person{0}@example.com'.format(n)) >>> CustomerFactory().email '[email protected]' >>> CustomerFactory().email '[email protected]' 

Relations class PostFactory(factory.Factory): class Meta: model = models.Post author = factory.SubFactory(CustomerFactory) 

Create Strategy # Builds and saves a Customer and a Post >>> post = PostFactory.create() >>> post.id is None # Post has been 'saved' False >>> post.author.id is None # post.author has been saved False 

Build Strategy # Builds but does not save a Customer, and then builds # but does not save a Post >>> post = PostFactory.build() >>> post.id is None True >>> post.author.id is None True 

ORM Support • Django, with DjangoModelFactory • Mogo, with MogoFactory • MongoEngine, with MongoEngineFactory • SQLAlchemy, with SQLAlchemyModelFactory 

References All the code examples and documentation have been taken from the official project website, available at http://factoryboy.readthedocs.org 

Thanks! Twitter: @andreagrandi