Guide to TDD & Flight to BDD with Python/Django

Talk presented at PyCon India 2012

Transcript

1. Guide to TDD & Flight to BDD with python/django
2. About Us Me: A humble student of the trade! You: ?
3. What I won't do? • Comparisons • No Mocking/DocTests • Opinions • Conclusions
4. What we will do? • Overview • Getting Started is Painful • Unit testing django models, views, forms • Integration testing with selenium • The shift to BDD • BDD Demo • Q & A
5. TDD - Initial Pain
6. About the topic
7. When & What & How
8. A basic unittest import unittest2 class TestDemo(unittest2.TestCase): " A demo of simple unit test" def setup(self): self.char = 'a' def tearDown(self): del self.char def test_first_pass(self): "Asserting that the character is not b" self.assertNotEqual(self.char, 'b') def test_second_fail(self): "Making a false assertion" assert self.char != 'c'
9. A good TDD sequence for a project 1. Write test for models a. the objects are being created and they have the desired relations as per specs b. the functions are returning correct values & manipulating db as per specs 2. Write test for forms - red, green a. states of forms b. perms. of good & bad forms, data 3. Write test for views a. response variable(200, 404) b. template & context variable c. behavior via decorator(@login_required etc.) 4. Write test for custom middlewares & template tags.
11. Fixture Management (& Namespaces) are one honking great idea -- let's do more of those!
12. A sample fixture test from django_dynamic_fixture import G class ChoiceModelTest(TestCase): def test_choice_creation(self): # set up the values poll0 = G(Poll) poll1 = G(Poll) ch0 = G(Choice, poll=poll0) ch1 = G(Choice, poll=poll0) # test basic values polls_in_db = Poll.objects.all() poll_zero = polls_in_db[0] poll_one = polls_in_db[1] choices = Choice.objects.filter(poll = poll_zero) self.assertEquals(choices.count(), 4) ch_zero = choices[0] self.assertEquals(ch_zero.choice, ch0.choice) self.assertEquals(ch_zero.votes, ch0.votes)
13. Test Runners
14. Settings for nose test runner TEST_RUNNER = 'django_nose. NoseTestSuiteRunner' NOSE_ARGS = [ '--with-coverage', '--cover-package=polls', '--with-progressive', '--verbosity=0', '--with-fixture-bundling', ]
15. Integration/Performance/System/Fun ctional/Web Tests
16. Integ. test with Selenium 1. Get the browser 2. Simulate Behavior a. use selectors i. locate by name, id, xpath, hyperlink test ii. browser extensions b. trigger keypress/action 3. Assert
17. Code
18. Behavior Driven Development (Sapir Whorf Hypothesis )
19. BDD - GWT/Gherkin Feature: Run or Riot In order to test my bot's strength, As a bot developer, I want to program my bot's decision making. Scenario: Boring Opponent Given the bots network has been trained When attacked by RA-One Then the bot should kill the opponent Scenario: Legendary opponent Given the bot's network has been trained When attacked by Robot Then the bot should bow down in respect! http://dannorth.net/whats-in-a-story/
20. .....although that may not be obvious at first unless you're Dutch.
21. BDD libraries • Lettuce - /gabrielfalcao/lettuce • Freshen - /rlisagor/freshen • Behave - /jeamland/behave • ...& counting.... (all above are format github.com/w+/w+)
22. BDD - Demo
23. Few more libraries • Another full featured testing tool - ◦ pytest.org • WSGI testing ◦ /pypi/WebTest • Test Discovery: ◦ /jezdez/django-discover-runner • Better Assertion Messages: ◦ /gabrielfalcao/sure
24. Practicality beats Purity In practical, the difference between theory & practical, is greater than, the difference between theory & practical, in theory.
25. Thanks & Questions?? • Contact ◦ at gamebit07 (twitter) ◦ gamebit07 at gmail dot com