Factory Boy - An alternative for Fixtures

Factory Boy is a fixtures replacement tool. It allows you to use objects customized for the current test, while only declaring the test-specific fields.

Setting up your factories:

For testing the Django app, create a root directory named tests. Then create __init__.py, tests.py (to write your tests), factories.py (to write your model factories) in that directory.

So, your app layout looks like:

  myapp
    |- __init__.py
    |- admin.py
    |- forms.py
    |- models.py
    |- tests
        |- __init__.py
        |- factories.py
        |- tests.py
    |- urls.py
    |- views.py

Features of Factory Boy:

It allows you to automate much of the testing scenarios. Some examples are:

  1. Use a 'Sequence' object using a lambda function to dynamically create unique field values:
        EX: username = factory.Sequence(lambda n: 'user_%d' % n)

  2. Use a LazyAttribute object to pick from a range of choices for a defined field
        EX: choice = factory.LazyAttribute(lambda s: random.choice(dict(MyModel.CHOICES).keys()))

A basic factory: Factories declare a set of attributes used to instantiate an object. Here's a basic factory that generates auth.User instances:

# factories.py
from factory import DjangoModelFactory, lazy_attribute
from django.contrib.auth.models import User

class UserFactory(DjangoModelFactory):
    first_name = 'Shirisha'
    last_name = 'Gaddi'
    username = factory.Sequence(lambda n: 'user_%d' % n)
    email = lazy_attribute(lambda obj: obj.username + "@example.com")

    class Meta:
        model = 'User'
        django_get_or_create = ('username',)

Calling this as factories.UserFactory() will perform same task as User.objects.create call. Howerver, it is possible to override the defined attributes by passing keyword arguments:

# Create a user instance by overriding first_name
user = factories.UserFactory(first_name="Karuna")

The factory's Meta has django_get_or_create set, which means the factory will call the Django built-in User.objects.get_or_create method.

Posted On 11 June 2015 By MicroPyramid


Need any Help in your Project?Let's Talk

Latest Comments
How to Create initial django migrations for existing DB schema.

Django provides the comfort database migrations from its version 1.8, with which we can avoid the usage of third party packages like south. Adding migrations ...

Continue Reading...
Django webpacker - A compression tool to bundles css, js files

django-webpacker is a django compressor tool which bundles css, js files to a single css, js file with webpack and updates your html files with ...

Continue Reading...
How to implement TokenBasedAuthentication in DjangoRestFramework?

This blog explains you how to use Token Authentication to authenticate users within a Django Application. Token Authentication is a way to authorize users by ...

Continue Reading...

Subscribe To our news letter

Subscribe and Stay Updated about our Webinars, news and articles on Django, Python, Machine Learning, Amazon Web Services, DevOps, Salesforce, ReactJS, AngularJS, React Native.
* We don't provide your email contact details to any third parties