Django testing an update post - django

Question

I receive this message "feed.models.Post.DoesNotExist: Post matching query does not exist." I believe it to be in the UpdatePost class I dont understand as there is a post created with an id of one. Why is this? Edit : I've added delete to fully test CRUD functionality
from django.test import TestCase, SimpleTestCase
from django.contrib.auth.models import User
from django.urls import reverse
from feed.models import Post
class Setup_Class(TestCase):
def setUp(self):
self.user = User.objects.create_user(username='jtur', email='jtur#accenture.com', password='onion')
user = User.objects.first()
Post.objects.create(title='test', content='more testing', author=user)
class PostTests(Setup_Class):
def test_content(self):
post = Post.objects.get(id=1)
expected_post_title = f'{post.title}'
expected_post_content = f'{post.content}'
self.assertEquals(expected_post_title, 'test')
self.assertEquals(expected_post_content, 'more testing')
def test_post_list_view(self):
response = self.client.get(reverse('feed-home'))
self.assertEqual(response.status_code, 200)
self.assertContains(response, 'more testing')
self.assertTemplateUsed(response, 'feed/home.html')
class UpdatePost(Setup_Class):
def test_post_update(self):
post = Post.objects.first()
post.title = "This has been changed"
expected_post_title = f'{post.title}'
self.assertEquals(expected_post_title, 'This has been changed')
def test_post_updated_view(self):
response = self.client.get(reverse('feed-home'))
self.assertEqual(response.status_code, 200)
self.assertContains(response, 'This has been changed')
self.assertTemplateUsed(response, 'feed/home.html')
class DeletePost(Setup_Class):
def test_post_delete(self):
post = Post.objects.first()
post.delete()
val = False
if post is None:
val = True
else:
val = False
self.assertTrue(val)
def test_post_list_view(self):
response = self.client.get(reverse('feed-home'))
self.assertEqual(response.status_code, 200)
self.assertNotContains(response, 'test')
self.assertTemplateUsed(response, 'feed/home.html')

Answer 1

There's no reason to assume the post created in your setUp method will have id=1. In fact, it probably won't after the first run of your tests. Even though the database is emptied after each run, the sequences are usually not reset.
You should get the first post with Post.objects.first() instead.
(Note however that your test_content and test_post_update methods are pretty pointless; they only call native Django functionality, which you don't need to test. Your tests should be concerned with testing your app's functionality, such as views that update or display the posts.)