Is there a boilerplate template for a TDD approach in Django-Python

Question

I’m working on a side a project while trying to discipline myself to get accustomed to the TDD approach in Django.

I'm not sure why I’m running into this failed test

(venv) osahenru@osahenru ~/D/q-4> pytest -k test_can_post_questions
============================= test session starts ==============================
platform linux -- Python 3.10.12, pytest-8.1.1, pluggy-1.5.0
django: version: 5.0.4, settings: config.settings (from ini)
rootdir: /home/osahenru/Documents/q-4
configfile: pytest.ini
plugins: django-4.8.0
collected 5 items / 4 deselected / 1 selected                                  

app/tests/test_views.py F                                                [100%]

=================================== FAILURES ===================================
______________________ TestEvent.test_can_post_questions _______________________

self = <test_views.TestEvent testMethod=test_can_post_questions>

    def test_can_post_questions(self):
        event = Event.objects.create(name='Python Ghana')
        data = {
            'text': 'how are you?',
        }
        response = self.client.post(reverse('questions', kwargs={'pk': event.id}), data)
>       self.assertIsInstance(response.context['form'], QuestionCreateForm)
E       TypeError: 'NoneType' object is not subscriptable

app/tests/test_views.py:52: TypeError
=========================== short test summary info ============================
FAILED app/tests/test_views.py::TestEvent::test_can_post_questions - TypeError: 'NoneType' object is not subscriptable
======================= 1 failed, 4 deselected in 0.53s ========================
(venv) osahenru@osahenru ~/D/q-4 [0|1]> 

here is the test causing the error message

def test_can_post_questions(self):
        event = Event.objects.create(name='Python Ghana')
        data = {
            'text': 'how are you?',
        }
        response = self.client.post(reverse('questions', kwargs={'pk': event.id}), data)
        self.assertIsInstance(response.context['form'], QuestionCreateForm)
        self.assertEqual(response.status_code, 302)

and here is the view function

def questions(request, pk):
    event = Event.objects.get(id=pk)
    questions = Question.objects.filter(event=event)
    
    form = QuestionCreateForm()
    if request.method == 'POST':
        form = QuestionCreateForm(request.POST)
        if form.is_valid():
            question = form.save(commit=False)
            question.event = event
            question.save()
            return redirect('questions', pk=pk)
        
    context = {
        'form': form,
        'questions': questions,
        'event': event
    }
    return render(request, 'questions.html', context)

Also as a beginner in the TDD approach, is there a boilerplate for writing unit tests in general and specifically for Django? I’m really struggling with this concept. Thanks

Answer 1

The response being tested here is the redirect after the post, which doesn't have a context. If you want to look at the context of the final response, you need to add follow=True to your self.client.post( call - see the docs for more about client args

As far as boilerplates go, the main rule of thumb I use is, if I wrote it, I test it. So you don't need to test a form's ability to submit, as django handles that and it's hopefully well tested already. To use your code as an example, I would test that the question.event item gets added as appropriate as that is your own addition to the default submit form process.