factory_boy Best Practices

1. Factories should represent their models

2. Do not rely on defaults from factories

   • If a default value is changed, all tests that depend on it will break
   • The setup of a test should contain all the logic to ensure it will always pass
   • Explicit better than implicit

3. Factories should contain only the required data

   • If the field is nullable (null=True) the attribute should be under a trait and not as a default value
   • If we want to have explicitly the attribute, we can use MyFactory(with_myattr=True)
   • When are we going to remember to test the case MyFactory(myattr=None)?
   • We should not assume there is an author when DB actually allows to not have it.

4. Build over create

   • MyFactory.build(): creates a local object (memory)
   • MyFactory.create(): creates a local object + stores it in the DB

5. If FK is in the table: SubFactor

   If FK is in the other table: RelatedFactory + trait

   • SubFactory: builds/creates the SubFactory during the process of creation of the main factory
   • RelatedFactory: builds/creates the RelatedFactory after creating the main factory

6. Use fixtures to wrap factories to avoid duplication

7. Avoid sharing factories or fixtures among different files

8. get_or_create should be used only for unique keys