Django valid_form() in UpdateView() not passing coverage report Unittest

Question

So i been trying to write a test for the form_valid() method of this view as you can see below But despited all the necessary assertions i've put in the test,it still fails to pass the coverage report and i can't see what exactly i might be missing in my test.

class CrView(UpdateView):
model = Model
form_class = Form_

def get_context_data(self, **kwargs):
    data = super().get_context_data(**kwargs)
    ........

@transaction.atomic()
def form_valid(self, form):
    context = self.get_context_data()
    items = context["items"]
    if items.is_valid():
        items.instance = self.object
        items.save()
        return super().form_valid(form)
    else:
        return self.form_invalid(form)

Unittest : Which all passes just fine

class TestsView(TestCase):
    def test_post(self):
     response_post = self.client.post(self.url, data={
        'string_set-TOTAL_FORMS': 1,
        'string_set-INITIAL_FORMS': 0,
        'string_set-MIN_NUM_FORMS': 0,
        'string_set-MAX_NUM_FORMS': 1000,
        'string_set-0-string': 'test',
        'string_set-0-page': self.page.uuid,

    })
    response_post_context= response_post.context['items']
    response_post_context.save(
        commit=True
    )
    # response_post_context = self.object
    self.assertEqual(response_post.status_code, 200)
    import pdb; pdb.set_trace()
    self.assertTrue(response_post_context.is_valid())
    self.assertEqual(response_post_context.instance, self.page)
    self.assertEqual(response_post_context.instance.number, 1)
    self.assertEqual(response_post_context.instance.pdf, self.pdf)
    self.assertEqual(response_post_context.instance.uuid, self.page.uuid)