Pytest & Django are really good friend

Slides of talk by Simone Dalla on testing of Django applications with pytest at Pycon7, DjangoVillage, Florence, Italy, April 2016.

Transcript

1. PYCON SETTE Florence, 17 April 2016 Pytest & Django are really good friends!!
2. PYCON SETTE about me Simone Dalla twitter @simodalla CTO @ SIA Unione dei Comuni Valli del Reno Lavino e Samoggia (Bologna, IT) Pythonista and Djangonauta
3. PYCON SETTE Topics: •testing and TDD overview •testing in Django overview •pytest and django-pytest intro •move from unittes to pytest https://simodalla@bitbucket.org/simodalla/pycon7_pytest_django.git
4. PYCON SETTE My first programmig book…
5. PYCON SETTE
6. PYCON SETTE credits: @ThePraticalDev You’re a 10x hacker and it must be someone else’s fault!!! More books…
7. PYCON SETTE All code is guilty… …until proven innocent!
8. PYCON SETTE Test my software? https://en.wikipedia.org/wiki/Software_testing Unit test Functional test Integration test Regression test Acceptance test etc…
9. credits: @ThePraticalDev Oh yes, is true, testing is cool… but…
10. PYCON SETTE Test Drive Development
11. PYCON SETTE Testing in Django unittest & django testing tools
12. PYCON SETTE from django.core.urlresolvers import reverse
 from django.utils import timezone
 from django.test import TestCase
 
 from ..models import Question class QuestionViewTests(TestCase):
 def test_index_view_with_no_questions(self):
 response = self.client.get(reverse('polls:index'))
 self.assertEqual(response.status_code, 200)
 self.assertContains(response, "No polls are available.")
 
 def test_index_view_with_a_past_question(self):
 create_question(question_text="Past question.", days=-30)
 response = self.client.get(reverse('polls:index'))
 self.assertQuerysetEqual(
 response.context['latest_question_list'],
 ['<Question: Past question.>']
 )
13. PYCON SETTE a mature full-featured Python testing tool
14. PYCON SETTE very pythonic tests & no boilerplate!
15. PYCON SETTE Plugin driven •pytest-django, Django integration •pytest-cov, coverage reporting •pytest-xdist, distributed/parallelized tests •… and more at:
 http://pytest.org/latest/plugins.html#external-plugins
16. PYCON SETTE many types of invocation: pytest - -help testing exception with context manager: raises marking test functions with attributes: markers monkeypatching/mocking modules and environments with fixture: monkeypatch many types of fixtures… Some cool features
17. PYCON SETTE $ mkvirtualenv pycon7_pytest_django $ workon pycon7_pytest_django $ pip install django pytest-django psycopg2 $ createdb pycon7_pytest_django $ django-admin startproject pycon7_pytest_django *** $ cd pycon7_pytest_django *** $ python manage.py startapp polls *** Demo time! $ git clone https://simodalla@bitbucket.org/simodalla/ pycon7_pytest_django.git $ git checkout 3f5316d ***
18. PYCON SETTE CODE…CODE…CODE… https://docs.djangoproject.com/en/1.9/intro
19. PYCON SETTE class Question(models.Model):
 question_text = models.CharField(max_length=200)
 pub_date = models.DateTimeField('date published')
 
 def was_published_recently(self):
 now = timezone.now()
 return now - datetime.timedelta(days=1) <= self.pub_date <= now
 was_published_recently.admin_order_field = 'pub_date'
 was_published_recently.boolean = True
 was_published_recently.short_description = 'Published recently?'
 
 
 class Choice(models.Model):
 question = models.ForeignKey('Question', on_delete=models.CASCADE)
 choice_text = models.CharField(max_length=200)
 votes = models.IntegerField(default=0) models.py $ git checkout 44bd202
20. PYCON SETTE class IndexView(generic.ListView):
 template_name = 'polls/index.html'
 context_object_name = 'latest_question_list'
 
 def get_queryset(self):
 """
 Return the last five published questions (not including those set to be published in the future).
 """
 return Question.objects.filter(
 pub_date__lte=timezone.now()).order_by('-pub_date')[:5]
 views.py $ git checkout 44bd202
21. PYCON SETTE def create_question(question_text, days):
 """
 Creates a question with the given `question_text` and published the
 given number of `days` offset to now (negative for questions published
 in the past, positive for questions that have yet to be published).
 """
 time = timezone.now() + datetime.timedelta(days=days)
 return Question.objects.create(question_text=question_text, pub_date=time) class QuestionMethodTests(TestCase):
 
 def test_was_published_recently_with_future_question(self):
 """
 was_published_recently() should return False for questions whose
 pub_date is in the future.
 """
 time = timezone.now() + datetime.timedelta(days=30)
 future_question = Question(pub_date=time)
 self.assertEqual(future_question.was_published_recently(), False) 
 class QuestionViewTests(TestCase):
 
 def test_index_view_with_a_past_question(self):
 """
 Questions with a pub_date in the past should be displayed on the
 index page.
 """
 create_question(question_text="Past question.", days=-30)
 response = self.client.get(reverse('polls:index'))
 self.assertQuerysetEqual(
 response.context['latest_question_list'],
 ['<Question: Past question.>']
 ) tests.py $ git checkout 44bd202
22. PYCON SETTE …demo time! $ python manage.py makemigrations $ python manage.py migrate $ python manage.py test Creating test database for alias 'default'... ........ ---------------------------------------------------- Ran 8 tests in 0.069s OK Destroying test database for alias 'default'...
23. PYCON SETTE $ touch pytest.ini py.test!! [pytest] DJANGO_SETTINGS_MODULE=pycon7_pytest_django.settings $ py.test polls/tests.py ============== test session starts =================================== platform darwin -- Python 3.5.1, pytest-2.9.1, py-1.4.31, pluggy-0.3.1 django settings: pycon7_pytest_django.settings (from ini file) rootdir: /Users/simo/PycharmProjects/pycon7_pytest_django, inifile: pytest.ini plugins: django-2.9.1 collected 8 items polls/tests.py ........ ============== 8 passed in 1.79 seconds =============================== $ git checkout 551305f
24. PYCON SETTE Django TestCase just works!!
25. PYCON SETTE By default, tests are found in test_*.py Discovery Just run doctest & unittes Run tests written for nose Discovery configuration in pytest.ini with: python_files = check_*.py
26. PYCON SETTE Test reorganization tests.py tests package $ git checkout 6b7b4b7
27. PYCON SETTE $ py.test ===================== test session starts ========================= platform darwin -- Python 3.5.1, pytest-2.9.1, py-1.4.31, pluggy-0.3.1 django settings: pycon7_pytest_django.settings (from ini file) rootdir: /Users/simo/PycharmProjects/pycon7_pytest_django, inifile: pytest.ini plugins: django-2.9.1 collected 8 items polls/tests/test_models.py ... polls/tests/test_views.py ..... ===================== 8 passed in 2.00 seconds ====================== Run all tests
28. PYCON SETTE $ py.test tests/ Run all the tests in a specific directory $ py.test -k test_foo Run all the tests cases that are named *test_foo* $ py.test —-durations=4 Run tests and show 4 slowest setup/test durations (0 for all) $ py.test —-n=4 Run tests in four parallel processses (plugin pytest-xdist) $ py.test —-reuse-db Reuse database from last run $ py.test —-reuse-db —-create-db Reuse database schema if models if changed Run tests…
29. PYCON SETTE # test_models.py
 
 import pytest def test_was_published_recently_with_future_question():
 pytest.fail()
 
 
 def test_was_published_recently_with_old_question():
 pytest.fail()
 
 
 def test_was_published_recently_with_recent_question():
 pytest.fail() unittest class $ git checkout ed46dd4 functions
30. PYCON SETTE $ git checkout 5df1f99 def test_was_published_recently_with_future_question(self):
 """
 was_published_recently() should return False for questions whose
 pub_date is in the future.
 """
 time = timezone.now() + datetime.timedelta(days=30)
 future_question = Question(pub_date=time)
 self.assertEqual(future_question.was_published_recently(), False) def test_was_published_recently_with_recent_question():
 time = timezone.now() - datetime.timedelta(hours=1)
 recent_question = Question(pub_date=time)
 assert recent_question.was_published_recently() is True testing with assert
31. PYCON SETTE $ git checkout c470411 @pytest.mark.parametrize("test_time,expected", [
 (timezone.now() + datetime.timedelta(days=30), False),
 (timezone.now() - datetime.timedelta(days=30), False),
 (timezone.now() - datetime.timedelta(hours=1), True),
 ])
 def test_was_published_recently(test_time, expected):
 question = Question(pub_date=test_time)
 assert question.was_published_recently() is expected tests parametrization $ py.test -v polls/tests/test_models.py::test_was_published_recently[test_time0-False] PASSED polls/tests/test_models.py::test_was_published_recently[test_time1-False] PASSED polls/tests/test_models.py::test_was_published_recently[test_time2-True] PASSED
32. PYCON SETTE $ git checkout a8eb54a # test_views.py class QuestionViewTests(TestCase):
 def test_index_view_with_no_questions(self):
 """
 If no questions exist, an appropriate message should be displayed.
 """
 response = self.client.get(reverse('polls:index'))
 self.assertEqual(response.status_code, 200)
 self.assertContains(response, "No polls are available.") @pytest.mark.django_db
 def test_index_view_with_no_questions(client):
 response = client.get(reverse('polls:index'))
 assert response.status_code == 200
 assert "No polls are available." in str(response.content) pytest-django & database
33. PYCON SETTE $ git checkout a8eb54a # no @pytest.mark.django_db def test_index_view_with_a_past_question(client):
 question = create_question(question_text="Past question.", days=-30)
 response = client.get(reverse('polls:index'))
 assert (list(response.context['latest_question_list']) == [question]) pytest-django & database $ py.test -v . . . test_views.py::test_index_view_with_a_past_question FAILED . . . Failed: Database access not allowed, use the "django_db" mark to enable it.
34. PYCON SETTE $ git checkout a8eb54a pytest fixtures != django fixtures @pytest.mark.django_db def test_index_view_with_a_past_question(client):
 question = create_question(question_text="Past question.", days=-30)
 response = client.get(reverse('polls:index'))
 assert (list(response.context['latest_question_list']) == [question])
35. PYCON SETTE django-pytest fixtures rf = instance of django.test.RequestFactory client = instance of django.test.Client admin_client = instance of django.test.Client that is logged in as an admin user admin_user = instance of a superuser, with username “admin” and password “password” django_user_model = user model used by Django django_username_field = field name used for the username on the user model db = ensure the Django database is set up transactional_db = database including transaction support live_server = runs a live Django server in a background thread settings = provide a handle on the django settings module
36. PYCON SETTE $ git checkout 4cecda0 pytest fixtures @pytest.fixture
 def question_in_the_past(db):
 return create_question(question_text="Past question.", days=-30)
 
 @pytest.fixture
 def question_in_the_future(db):
 return create_question(question_text="Future question.", days=30)
 
 @pytest.fixture
 def two_questions_in_the_past(db):
 return [create_question(question_text="Past question 1.", days=-30),
 create_question(question_text="Past question 2.", days=-5)] @pytest.mark.django_db def test_index_view_with_a_past_question(
 self, client, question_in_the_past):
 response = client.get(reverse('polls:index'))
 assert list(response.context['latest_question_list']) == [
 question_in_the_past] re
37. PYCON SETTE Good idea!?! …“test of test” , another tests for complicated or critical fixtures.
38. PYCON SETTE my 2 cent on django fixtures… …use factory_boy!!! $ pip install factory_boy @pytest.fixture
 def two_questions_in_the_past(db):
 return [QuestionFactory.build(question_text=“Past question 1.", days=-30),
 QuestionFactory.build(question_text="Past question 2.", days=-5)] http://factoryboy.readthedocs.org/en/latest/index.html
39. PYCON SETTE last my 2 cent on pytest and django… …works with both worlds!
40. PYCON SETTE Crowdfunding a dev sprint in June 2016 for pytest 3.0 (+ tox) https://www.indiegogo.com/projects/python-testing-sprint-mid-2016 http://pytest.org/latest/announce/sprint2016.html
41. PYCON SETTE More info? Help? Docs? Florian Bruhin, pytest - Rapid Simple Testing - Swiss Python Summit 2016 https://www.youtube.com/watch?v=rCBHkQ_LVIs Holger Krekel, Improving automated testing with py.test - PyCon 2014
 
 https://www.youtube.com/watch?v=AiThU6JQbE8
 Andreas Pelme, Pytest: help you write better Django apps, DjangoCon Europe 2014
 
 https://www.youtube.com/watch?v=aaArYVh6XSM
 official Django testing documentation
 
 https://docs.djangoproject.com/en/1.9/topics/testing/
 pytest documentation
 
 http://pytest.org/
 pytest-django documentation
 
 https://pytest-django.readthedocs.org
42. PYCON SETTE twitter @simodalla github simodalla slides http://speakerdeck.com/simodalla Thank you!