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https://github.com/FactoryBoy/factory_boy

A test fixtures replacement for Python
https://github.com/FactoryBoy/factory_boy

django fixtures hacktoberfest python sqlalchemy testing

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A test fixtures replacement for Python

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README 

        
factory_boy

===========



.. image:: https://github.com/FactoryBoy/factory_boy/workflows/Test/badge.svg

    :target: https://github.com/FactoryBoy/factory_boy/actions?query=workflow%3ATest



.. image:: https://github.com/FactoryBoy/factory_boy/workflows/Check/badge.svg

    :target: https://github.com/FactoryBoy/factory_boy/actions?query=workflow%3ACheck



.. image:: https://img.shields.io/pypi/v/factory_boy.svg

    :target: https://factoryboy.readthedocs.io/en/latest/changelog.html

    :alt: Latest Version



.. image:: https://img.shields.io/pypi/pyversions/factory_boy.svg

    :target: https://pypi.org/project/factory-boy/

    :alt: Supported Python versions



.. image:: https://img.shields.io/pypi/wheel/factory_boy.svg

    :target: https://pypi.org/project/factory-boy/

    :alt: Wheel status



.. image:: https://img.shields.io/pypi/l/factory_boy.svg

    :target: https://github.com/FactoryBoy/factory_boy/blob/master/LICENSE

    :alt: License



factory_boy is a fixtures replacement based on thoughtbot's `factory_bot `_.



As a fixtures replacement tool, it aims to replace static, hard to maintain fixtures

with easy-to-use factories for complex objects.



Instead of building an exhaustive test setup with every possible combination of corner cases,

``factory_boy`` allows you to use objects customized for the current test,

while only declaring the test-specific fields:



.. code-block:: python



    class FooTests(unittest.TestCase):



        def test_with_factory_boy(self):

            # We need a 200€, paid order, shipping to australia, for a VIP customer

            order = OrderFactory(

                amount=200,

                status='PAID',

                customer__is_vip=True,

                address__country='AU',

            )

            # Run the tests here



        def test_without_factory_boy(self):

            address = Address(

                street="42 fubar street",

                zipcode="42Z42",

                city="Sydney",

                country="AU",

            )

            customer = Customer(

                first_name="John",

                last_name="Doe",

                phone="+1234",

                email="[email protected]",

                active=True,

                is_vip=True,

                address=address,

            )

            # etc.



factory_boy is designed to work well with various ORMs (Django, MongoDB, SQLAlchemy),

and can easily be extended for other libraries.



Its main features include:



- Straightforward declarative syntax

- Chaining factory calls while retaining the global context

- Support for multiple build strategies (saved/unsaved instances, stubbed objects)

- Multiple factories per class support, including inheritance



Links

-----



* Documentation: https://factoryboy.readthedocs.io/

* Repository: https://github.com/FactoryBoy/factory_boy

* Package: https://pypi.org/project/factory-boy/

* Mailing-list: `[email protected] `_ | https://groups.google.com/forum/#!forum/factoryboy



Download

--------



PyPI: https://pypi.org/project/factory-boy/



.. code-block:: sh



    $ pip install factory_boy



Source: https://github.com/FactoryBoy/factory_boy/



.. code-block:: sh



    $ git clone git://github.com/FactoryBoy/factory_boy/

    $ python setup.py install



Usage

-----



.. note:: This section provides a quick summary of factory_boy features.

          A more detailed listing is available in the full documentation.



Defining factories

""""""""""""""""""



Factories declare a set of attributes used to instantiate a Python object.

The class of the object must be defined in the ``model`` field of a ``class Meta:`` attribute:



.. code-block:: python



    import factory

    from . import models



    class UserFactory(factory.Factory):

        class Meta:

            model = models.User



        first_name = 'John'

        last_name = 'Doe'

        admin = False



    # Another, different, factory for the same object

    class AdminFactory(factory.Factory):

        class Meta:

            model = models.User



        first_name = 'Admin'

        last_name = 'User'

        admin = True



ORM integration

"""""""""""""""



factory_boy integration with Object Relational Mapping (ORM) tools is provided

through specific ``factory.Factory`` subclasses:



* Django, with ``factory.django.DjangoModelFactory``

* Mogo, with ``factory.mogo.MogoFactory``

* MongoEngine, with ``factory.mongoengine.MongoEngineFactory``

* SQLAlchemy, with ``factory.alchemy.SQLAlchemyModelFactory``



More details can be found in the ORM section.



Using factories

"""""""""""""""



factory_boy supports several different instantiation strategies: build, create, and stub:



.. code-block:: python



    # Returns a User instance that's not saved

    user = UserFactory.build()



    # Returns a saved User instance.

    # UserFactory must subclass an ORM base class, such as DjangoModelFactory.

    user = UserFactory.create()



    # Returns a stub object (just a bunch of attributes)

    obj = UserFactory.stub()



You can use the Factory class as a shortcut for the default instantiation strategy:



.. code-block:: python



    # Same as UserFactory.create()

    user = UserFactory()



No matter which strategy is used, it's possible to override the defined attributes by passing keyword arguments:



.. code-block:: pycon



    # Build a User instance and override first_name

    >>> user = UserFactory.build(first_name='Joe')

    >>> user.first_name

    "Joe"



It is also possible to create a bunch of objects in a single call:



.. code-block:: pycon



    >>> users = UserFactory.build_batch(10, first_name="Joe")

    >>> len(users)

    10

    >>> [user.first_name for user in users]

    ["Joe", "Joe", "Joe", "Joe", "Joe", "Joe", "Joe", "Joe", "Joe", "Joe"]



Realistic, random values

""""""""""""""""""""""""



Demos look better with random yet realistic values; and those realistic values can also help discover bugs.

For this, factory_boy relies on the excellent `faker `_ library:



.. code-block:: python



    class RandomUserFactory(factory.Factory):

        class Meta:

            model = models.User



        first_name = factory.Faker('first_name')

        last_name = factory.Faker('last_name')



.. code-block:: pycon



    >>> RandomUserFactory()

    



Reproducible random values

""""""""""""""""""""""""""



The use of fully randomized data in tests is quickly a problem for reproducing broken builds.

To that purpose, factory_boy provides helpers to handle the random seeds it uses, located in the ``factory.random`` module:



.. code-block:: python



    import factory.random



    def setup_test_environment():

        factory.random.reseed_random('my_awesome_project')

        # Other setup here



Lazy Attributes

"""""""""""""""



Most factory attributes can be added using static values that are evaluated when the factory is defined,

but some attributes (such as fields whose value is computed from other elements)

will need values assigned each time an instance is generated.



These "lazy" attributes can be added as follows:



.. code-block:: python



    class UserFactory(factory.Factory):

        class Meta:

            model = models.User



        first_name = 'Joe'

        last_name = 'Blow'

        email = factory.LazyAttribute(lambda a: '{}.{}@example.com'.format(a.first_name, a.last_name).lower())

        date_joined = factory.LazyFunction(datetime.now)



.. code-block:: pycon



    >>> UserFactory().email

    "[email protected]"



.. note:: ``LazyAttribute`` calls the function with the object being constructed as an argument, when

          ``LazyFunction`` does not send any argument.



Sequences

"""""""""



Unique values in a specific format (for example, e-mail addresses) can be generated using sequences. Sequences are defined by using ``Sequence`` or the decorator ``sequence``:



.. code-block:: python



    class UserFactory(factory.Factory):

        class Meta:

            model = models.User



        email = factory.Sequence(lambda n: 'person{}@example.com'.format(n))



    >>> UserFactory().email

    '[email protected]'

    >>> UserFactory().email

    '[email protected]'



Associations

""""""""""""



Some objects have a complex field, that should itself be defined from a dedicated factories.

This is handled by the ``SubFactory`` helper:



.. code-block:: python



    class PostFactory(factory.Factory):

        class Meta:

            model = models.Post



        author = factory.SubFactory(UserFactory)



The associated object's strategy will be used:



.. code-block:: python



    # Builds and saves a User and a Post

    >>> post = PostFactory()

    >>> post.id is None  # Post has been 'saved'

    False

    >>> post.author.id is None  # post.author has been saved

    False



    # Builds but does not save a User, and then builds but does not save a Post

    >>> post = PostFactory.build()

    >>> post.id is None

    True

    >>> post.author.id is None

    True



Support Policy

--------------



``factory_boy`` supports active Python versions as well as PyPy3.



- **Python**'s `supported versions

  `__.

- **Django**'s `supported

  versions `__.

- **SQLAlchemy**: `latest version on PyPI `__.

- **MongoEngine**: `latest version on PyPI `__.



Debugging factory_boy

---------------------



Debugging factory_boy can be rather complex due to the long chains of calls.

Detailed logging is available through the ``factory`` logger.



A helper, `factory.debug()`, is available to ease debugging:



.. code-block:: python



    with factory.debug():

        obj = TestModel2Factory()



    import logging

    logger = logging.getLogger('factory')

    logger.addHandler(logging.StreamHandler())

    logger.setLevel(logging.DEBUG)



This will yield messages similar to those (artificial indentation):



.. code-block:: ini



    BaseFactory: Preparing tests.test_using.TestModel2Factory(extra={})

      LazyStub: Computing values for tests.test_using.TestModel2Factory(two=>)

        SubFactory: Instantiating tests.test_using.TestModelFactory(__containers=(,), one=4), create=True

        BaseFactory: Preparing tests.test_using.TestModelFactory(extra={'__containers': (,), 'one': 4})

          LazyStub: Computing values for tests.test_using.TestModelFactory(one=4)

          LazyStub: Computed values, got tests.test_using.TestModelFactory(one=4)

        BaseFactory: Generating tests.test_using.TestModelFactory(one=4)

      LazyStub: Computed values, got tests.test_using.TestModel2Factory(two=)

    BaseFactory: Generating tests.test_using.TestModel2Factory(two=)



Contributing

------------



factory_boy is distributed under the MIT License.



Issues should be opened through `GitHub Issues `_; whenever possible, a pull request should be included.

Questions and suggestions are welcome on the `mailing-list `_.



Development dependencies can be installed in a `virtualenv

`_ with:



.. code-block:: sh



    $ pip install --editable '.[dev]'



All pull requests should pass the test suite, which can be launched simply with:



.. code-block:: sh



    $ make testall



In order to test coverage, please use:



.. code-block:: sh



    $ make coverage



To test with a specific framework version, you may use a ``tox`` target:



.. code-block:: sh



    # list all tox environments

    $ tox --listenvs



    # run tests inside a specific environment (django/mongoengine/SQLAlchemy are not installed)

    $ tox -e py310



    # run tests inside a specific environment (django)

    $ tox -e py310-djangomain

    $ tox -e py310-djangomain-postgres



    # run tests inside a specific environment (alchemy)

    $ tox -e py310-alchemy

    $ tox -e py310-alchemy-postgres



    # run tests inside a specific environment (mongoengine)

    $ tox -e py310-mongo



Packaging

---------



For users interesting in packaging FactoryBoy into downstream distribution channels

(e.g. ``.deb``, ``.rpm``, ``.ebuild``), the following tips might be helpful:



Dependencies

""""""""""""



The package's run-time dependencies are listed in ``setup.cfg``.

The dependencies useful for building and testing the library are covered by the

``dev`` and ``doc`` extras.



Moreover, all development / testing tasks are driven through ``make(1)``.



Building

""""""""



In order to run the build steps (currently only for docs), run:



.. code-block:: sh



    python setup.py egg_info

    make doc



Testing

"""""""



When testing for the active Python environment, run the following:



.. code-block:: sh



    make test



.. note::



    You must make sure that the ``factory`` module is importable, as it is imported from

    the testing code.