[PYTHON] Pin factory_boy seed value in Django

Conclusion

Create a custom class that inherits from TestCase and set the seed value insetUp (). Each app inherits a custom class and writes a test.

background

I wanted to ensure test reproducibility when using factory_boy with Django.

procedure

environment

factory-boy==2.12.0

BaseTestCase class definition

Define a BaseTestCase class that fixes the seed value. I write a base application and write abstract classes there.

python:./base/tests.py

from django.test import TestCase
import factory.random


class BaseTestCase(TestCase):
    def setUp(self):
        factory.random.reseed_random(0)
        return super().setUp()

Inheritance of individual TestCase classes

Inherit the BaseTestCase class and define each test case.

python:./user/tests.py

from base.tests import BaseTestCase

from .models import User
from .factories import UserFactory


class UserTestCase(BaseTestCase):
    def test_create_user(self):
        user = UserFactory()
        actual_user = User.objects.get(pk=user.pk)
        self.assertEqual(user, actual_user)

Of course, when defining setUp (), also call the method of the parent class.

python:./user/tests.py

class UserTestCase(BaseTestCase):
    def setUp(self):
        super().setUp()
        print("initialize")

    def test_create_user(self):
        user = UserFactory()
        actual_user = User.objects.get(pk=user.pk)
        self.assertEqual(user, actual_user)

Summary

By fixing the seed value, the test can be executed with the reproducibility guaranteed. This article is based on Django, but it should work for Django as well.