Django returns empty QuerySet in the tests - django-testing

Question

I'm trying to make a test for this view:
def author_detail(request, pk):
author = get_object_or_404(Author, pk=pk)
blog = author.blog_set.all()
paginator = Paginator(blog, 1)
page_number = request.GET.get('page')
page_obj = paginator.get_page(page_number)
context = {
'author': author,
'page_obj': page_obj,
}
return render(request, 'blog/author_detail.html', context=context)
The view is working normally. My problem is when I'm going to try to test this view. Here my test:
class AuthorDetailViewTest(TestCase):
def setUp(self):
user = User.objects.create(username='user01', password='123456')
self.author_instance = Author.objects.create(
user=user, date_of_birth='1998-09-08', bio='I am user01')
topic = Topic.objects.create(name='Testing')
Blog.objects.create(title='My blog', content="It's my blog")
Blog.author = self.author_instance
Blog.topic = topic
# The author.blog_set.all() are returning an empty QuerySet
# This problem are only happening in the tests, not in the view
def test_pagination_first_page(self):
response = self.client.get(
reverse('author-detail', kwargs={'pk':self.author_instance.pk}))
self.assertEqual(len(response.context['page_obj']), 1)
The result are:
FAIL: test_pagination_first_page (blog.tests.test_views.AuthorDetailViewTest)
-------------------------------------------------------------------
Traceback (most recent call last):
File "/home/carlos/problem/venv_01/the_blog/blog/tests/test_views.py", line 189,in test_pagination_first_page
self.assertEqual(len(response.context['page_obj']), 1)
AssertionError: 0 != 1
----------------------------------------------------------------------
The len(response.context['page_obj']) is equal 0. It should be at least 1, because I created one Blog object. When I print the QuerySet of author.blog_set.all(), the returned QuerySet are empty (<QuerySet []>). I think that the problem is in the creation of the Blog model, because the author and topic fields are ManyToManyField.
As I mentioned before, my problem is in the test, not in the view. The view is working normally.

Answer 1

The last 3 lines of the following code snippet have some issues:
def setUp(self):
user = User.objects.create(username='user01', password='123456')
self.author_instance = Author.objects.create(
user=user, date_of_birth='1998-09-08', bio='I am user01')
topic = Topic.objects.create(name='Testing')
Blog.objects.create(title='My blog', content="It's my blog")
Blog.author = self.author_instance
Blog.topic = topic
The blog object is created but never returned/fetched
Blog model is being used to connect author and topic. Instead, the blog object should be used.
Author and Topic are M2M on Blog. The new objects should be added via add method. See How to add data into ManyToMany field? for additional context.

Answer 2

Solution:
def setUp(self):
user = User.objects.create(username='user01', password='123456')
author = Author.objects.create(
user=user, date_of_birth='1998-09-08', bio='I am user01')
blog = Blog.objects.create(
title='My blog', content="It's my blog")
blog.author.add(author)
blog.topic.add(topic)
It worked.