ERROR: setUpClass (apps.books.tests.test_permissions.ReadOnlyPermissionsTest)
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Traceback (most recent call last):
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/django/test/testcases.py", line 1017, in setUpClass
    cls.setUpTestData()
  File "/home/oleh/work/literaclub/backend/apps/books/tests/base.py", line 229, in setUpTestData
    super().setUpTestData()
  File "/home/oleh/work/literaclub/backend/apps/books/tests/base.py", line 54, in setUpTestData
    cls.user_normal_one = UserFactory()
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/factory/base.py", line 46, in __call__
    return cls.create(**kwargs)
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/factory/base.py", line 563, in create
    return cls._generate(enums.CREATE_STRATEGY, kwargs)
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/factory/base.py", line 500, in _generate
    return step.build()
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/factory/builder.py", line 279, in build
    kwargs=kwargs,
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/factory/base.py", line 314, in instantiate
    return self.factory._create(model, *args, **kwargs)
  File "/home/oleh/work/literaclub/backend/apps/books/tests/factories.py", line 41, in _create
    return manager.create_user(*args, **kwargs)
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/django/contrib/auth/models.py", line 150, in create_user
    return self._create_user(username, email, password, **extra_fields)
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/django/contrib/auth/models.py", line 140, in _create_user
    email = self.normalize_email(email)
  File "/home/oleh/work/literaclub/backend/venv/lib/python3.6/site-packages/django/contrib/auth/base_user.py", line 25, in normalize_email
    email_name, domain_part = email.strip().rsplit('@', 1)
AttributeError: 'tuple' object has no attribute 'strip'