Pytest-django - testing creation and passing a required User object - django

Question

Apologies if this has already been answered elsewhere. I cannot find an answer which I can retrofit into my situation.
I'm new to django so I feel the problem is me not getting a fundamental grasp of a presumably basic concept here...
Using DRF and pytest-django, i'm trying to be diligent and write tests along the way before it becomes too time consuming to manually test. I can see it snowballing pretty quickly.
The issue I face is when I try to test the creation of a Catalogue, I can't get it to pass an User instance to the mandatory field 'created_by'. The logic works fine when I test manually, but writing the test itself is causing me headaches.
Many thanks in advance!
The error is:
TypeError: Cannot encode None for key 'created_by' as POST data. Did you mean to pass an empty string or omit the value?
Code provided.
# core/models.py
from django.contrib.auth.models import AbstractUser
class User(AbstractUser):
email = models.EmailField(unique=True)
# workshop/models.py
from django.conf import settings
from django.db import models
class Catalogue(models.Model):
STATE_DRAFT = 'DRAFT'
STATE_PUBLISHED_PRIVATE = 'PUBPRIV'
STATE_PUBLISHED_PUBLIC = 'PUBPUB'
STATE_CHOICES = [
(STATE_DRAFT, 'Draft'),
(STATE_PUBLISHED_PRIVATE, 'Published (Private)'),
(STATE_PUBLISHED_PUBLIC, 'Published (Public)')
]
company = models.ForeignKey(Company, on_delete=models.PROTECT)
title = models.CharField(max_length=255)
description = models.TextField(null=True, blank=True)
state = models.CharField(
max_length=10, choices=STATE_CHOICES, default=STATE_DRAFT)
created_by = models.ForeignKey(
settings.AUTH_USER_MODEL, on_delete=models.PROTECT)
created_on = models.DateTimeField(auto_now_add=True)
def __str__(self) -> str:
return self.title
class CatalogueItem(models.Model):
TYPE_GOODS = 'GOODS'
TYPE_SERVICES = 'SERVICES'
TYPE_GOODS_AND_SERVICES = 'GOODS_AND_SERVICES'
TYPE_CHOICES = [
(TYPE_GOODS, 'Goods'),
(TYPE_SERVICES, 'Services'),
(TYPE_GOODS_AND_SERVICES, 'Goods & Services')
]
catalogue = models.ForeignKey(
Catalogue, on_delete=models.CASCADE, related_name='catalogueitems')
type = models.CharField(
max_length=50, choices=TYPE_CHOICES, default=TYPE_GOODS)
name = models.CharField(max_length=255)
description = models.TextField()
unit_price = models.DecimalField(max_digits=9, decimal_places=2)
can_be_discounted = models.BooleanField(default=True)
def __str__(self) -> str:
return self.name
#property
def item_type(self):
return self.get_type_display()
# workshop/serializers.py
class CatalogueSerializer(serializers.ModelSerializer):
catalogueitems = SimpleCatalogueItemSerializer(
many=True, read_only=True)
created_on = serializers.DateTimeField(read_only=True)
created_by = serializers.PrimaryKeyRelatedField(read_only=True)
class Meta:
# depth = 1
model = Catalogue
fields = ['id', 'title', 'description',
'state', 'catalogueitems', 'created_by', 'created_on']
def create(self, validated_data):
company_id = self.context['company_id']
user = self.context['user']
return Catalogue.objects.create(company_id=company_id, created_by=user, **validated_data)
# workshop/views.py
class CatalogueViewSet(ModelViewSet):
serializer_class = CatalogueSerializer
def get_permissions(self):
if self.request.method in ['PATCH', 'PUT', 'DELETE', 'POST']:
return [IsAdminUser()]
return [IsAuthenticated()]
def get_queryset(self):
user = self.request.user
if user.is_staff:
return Catalogue.objects.prefetch_related('catalogueitems__catalogue').filter(company_id=self.kwargs['company_pk'])
elif user.is_authenticated:
return Catalogue.objects.filter(company_id=self.kwargs['company_pk'], state='PUBPUB')
def get_serializer_context(self):
company_id = self.kwargs['company_pk']
return {'company_id': company_id, 'user': self.request.user}
# workshop/tests/conftest.py
from core.models import User
from rest_framework.test import APIClient
import pytest
#pytest.fixture
def api_client():
return APIClient()
#pytest.fixture
def authenticate(api_client):
def do_authenticate(is_staff=False):
return api_client.force_authenticate(user=User(is_staff=is_staff))
return do_authenticate
# workshop/tests/test_catalogues.py
from core.models import User
from workshop.models import Catalogue
from rest_framework import status
import pytest
#pytest.fixture
def create_catalogue(api_client):
def do_create_catalogue(catalogue):
return api_client.post('/companies/1/catalogues/', catalogue)
return do_create_catalogue
class TestCreateCatalogue:
def test_if_admin_can_create_catalogue_returns_201(self, authenticate, create_catalogue):
user = authenticate(is_staff=True)
response = create_catalogue(
{'title': 'a', 'description': 'a', 'state': 'DRAFT','created_by':user})
assert response.status_code == status.HTTP_201_CREATED

Answer 1

I think you may have a problem with the user that you are using to do the test,
when you call authenticate it returns a client which is not the same as a user.
then you run the authenticate and log in as a generic user. Try making another fixture that creates a user first, authenticate with that user to return the client and then post that user you created to create_catalogue
from django.conf import settings
#pytest.fixture
def create_user() -> User:
return settings.AUTH_USER_MODEL.objects.create(
username="Test User", password="Test Password", email="testuser#example.com"
)
#pytest.fixture
def authenticate(api_client):
def do_authenticate(create_user):
return api_client.force_authenticate(create_user)
return do_authenticate
class TestCreateCatalogue:
def test_if_admin_can_create_catalogue_returns_201(self, authenticate, create_user create_catalogue):
user = authenticate(create_user)
response = create_catalogue(
{'title': 'a', 'description': 'a', 'state': 'DRAFT','created_by':create_user})
assert response.status_code == status.HTTP_201_CREATED