Django Testing

Django Testing Eric Holscher http://ericholscher.com Tuesday, May 5, 2009 1

How do you know? • First 4 months of my job was porting and testing Ellington • Going from Django r1290 to Django 1.0. • Suite from 0 to 400 tests. Tuesday, May 5, 2009 2

30,000 Ft View • State of testing in Django • Why you should be testing • How you start testing • Useful tools • Eventual Goals Tuesday, May 5, 2009 3

State of Django Testing Tuesday, May 5, 2009 4

assertTrue('Hello World', community.testing.status) Tuesday, May 5, 2009 5

Django 1.1 Making Testing Possible since 2009 Tuesday, May 5, 2009 6

manage.py startapp creates a tests.py Tuesday, May 5, 2009 7

from django.test import TestCase class SimpleTest(TestCase): def test_basic_addition(self): quot;quot;quot; Tests that 1 + 1 always equals 2. quot;quot;quot; self.failUnlessEqual(1 + 1, 2) __test__ = {quot;doctestquot;: quot;quot;quot; Another way to test that 1 + 1 is equal to 2. >>> 1 + 1 == 2 True quot;quot;quot;} Tuesday, May 5, 2009 8

Fast Tests (Transactions) Tuesday, May 5, 2009 9

Minutes (Lower is better) Ellington Test Speedup 60 45 30 15 0 Django 1.0 Django 1.1 Tuesday, May 5, 2009 10

You now have no excuse. Tuesday, May 5, 2009 11

Why to test Tuesday, May 5, 2009 12

Scary Tuesday, May 5, 2009 13

Less Scary Tuesday, May 5, 2009 14

Not Scary Tuesday, May 5, 2009 15

Peace of Mind Tuesday, May 5, 2009 16

Code must adapt Tuesday, May 5, 2009 17

“It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.” - Charles Darwin Tuesday, May 5, 2009 18

Won’t somebody please think of the users?! Tuesday, May 5, 2009 19

Tests as Documentation Tuesday, May 5, 2009 20

Tests as Documentation Test driven development + Document driven development = Test Driven Documentation Tuesday, May 5, 2009 20

“Code without tests is broken as designed” - Jacob Kaplan-Moss Tuesday, May 5, 2009 21

Dizzying Array of Testing Options Tuesday, May 5, 2009 22

What kind of test? • doctest • unittest Tuesday, May 5, 2009 23

Doctests • Inline documentation • <Copy from terminal to test ﬁle> • Can’t use PDB • Hide real failures • “Easy” Tuesday, May 5, 2009 24

def parse_ttag(token, required_tags): quot;quot;quot; A function to parse a template tag. It sets the name of the tag to 'tag_name' in the hash returned. >>> from test_utils.templatetags.utils import parse_ttag >>> parse_ttag('super_cool_tag for my_object as obj', ['as']) {'tag_name': u'super_cool_tag', u'as': u'obj'} >>> parse_ttag('super_cool_tag for my_object as obj', ['as', 'for']) {'tag_name': u'super_cool_tag', u'as': u'obj', u'for': u'my_object'} quot;quot;quot; bits = token.split(' ') tags = {'tag_name': bits.pop(0)} for index, bit in enumerate(bits): bit = bit.strip() if bit in required_tags: if len(bits) != index-1: tags[bit] = bits[index+1] return tags Tuesday, May 5, 2009 25

Unit Tests • Use for everything else • More rubust • setUp and tearDown • Standard (XUnit) Tuesday, May 5, 2009 26

import random import unittest class TestRandom(unittest.TestCase): def setUp(self): self.seq = range(10) def testshuffle(self): # make sure the shuffled sequence does not lose any elements random.shuffle(self.seq) self.seq.sort() self.assertEqual(self.seq, range(10)) if __name__ == '__main__': unittest.main() Tuesday, May 5, 2009 27

Django TestCase • Subclasses unittest • Fixtures • Assertions • Mail • URLs Tuesday, May 5, 2009 28

Test Client • Test HTTP Requests without server • Test Views, Templates, and Context Tuesday, May 5, 2009 29

from django.contrib.auth.models import User from django.test import TestCase from django.core import mail class PasswordResetTest(TestCase): fixtures = ['authtestdata.json'] urls = 'django.contrib.auth.urls' def test_email_not_found(self): quot;Error is raised if the provided email address isn't currently registeredquot; response = self.client.get('/password_reset/') self.assertEquals(response.status_code, 200) response = self.client.post('/password_reset/', {'email': 'not_a_real_email@email.com'}) self.assertContains(response, quot;That e-mail address doesn't have an associated user accountquot;) self.assertEquals(len(mail.outbox), 0) Tuesday, May 5, 2009 30

What ﬂavor of test? • Unit • Functional • Browser Tuesday, May 5, 2009 31

Unit test • Low level tests • Small, focused, exercising one bit of functionality Tuesday, May 5, 2009 32

Regression test • Written when you ﬁnd a bug • Proves bug was ﬁxed • Django Tickets Tuesday, May 5, 2009 33

Functional • “Black Box Testing” • Check High Level Functionality Tuesday, May 5, 2009 34

Functional Testing Tools • Twill • Django Test Client • ... Tuesday, May 5, 2009 35

Ellington • Lots of different clients • Need to test deployment (Functional) Tuesday, May 5, 2009 36

go {{ site.url }}/marketplace/search/ formvalue 1 q pizza submit code 200 Tuesday, May 5, 2009 37

Tuesday, May 5, 2009 38

Pretty Functional Tests Tuesday, May 5, 2009 39

Can test • All sites on a server • All sites of a certain type • A single problemed client • A test across all sites Tuesday, May 5, 2009 40

Browser tests • Run tests in a web browser • Check compatibility of design • Basically an IE sanity check • Only real way to test JS, AJAX, CSS Tuesday, May 5, 2009 41

Browser Testing Tools • Windmill • Selenium Tuesday, May 5, 2009 42

Other kinds of testing • Spiders • Fuzz testing • Load testing • Prayer Tuesday, May 5, 2009 44

Where do I start? Tuesday, May 5, 2009 45

Fixed a bug Tuesday, May 5, 2009 46

Poking at code on the command line Tuesday, May 5, 2009 47

Pony turned Horse Tuesday, May 5, 2009 48

Now what? Tuesday, May 5, 2009 49

Start with a regression test or a functional test Tuesday, May 5, 2009 50

Use unittest unless you have a reason not to! Tuesday, May 5, 2009 51

Use the data, Luke • Use data as a pivot • Fixtures means you use Unit Tests • Creation on the command line, Doctests Tuesday, May 5, 2009 52

Creating Fixtures • ./manage.py dumpdata <app> • ./manage.py makeﬁxture Model[x:y] • Follows relations • By Hand Tuesday, May 5, 2009 53

TestShell ./manage.py testshell <ﬁxture> Tuesday, May 5, 2009 54

Making Functional tests • Usually a relatively annoying process • Testmaker makes it easy. • ./manage.py testmaker <app> • Simply browse and your session is recorded. Tuesday, May 5, 2009 55

Testing your views generally gets you the most coverage. Tuesday, May 5, 2009 56

80% Case Tuesday, May 5, 2009 57

When > Where Tuesday, May 5, 2009 58

Tools Tuesday, May 5, 2009 59

Coverage Tuesday, May 5, 2009 60

Mock Objects • http://www.voidspace.org.uk/python/mock/ Tuesday, May 5, 2009 62

import unittest from mock import Mock from templatetags.cms_tags import if_link_is_active, IsActiveNode class TestIsActiveTag(unittest.TestCase): def test_returns_correct_node_type(self): token = Mock(methods=['split_contents']) token.split_contents.return_value = ('if_link_is_active', 'bar') self.assertEqual(type(if_link_is_active(Mock(), token)), IsActiveNode) Tuesday, May 5, 2009 63

Custom Test Runners Tuesday, May 5, 2009 64

Django Test Extensions • Gareth Rushgrove • Extra Assertions • Coverage and XML Test Runners • http://github.com/garethr/django-test-extensions Tuesday, May 5, 2009 65

Django Sane Testing • Ella Folk, Lucas (Hi!) • Based on nosetests • Selenium • Live server • http://devel.almad.net/trac/django-sane-testing/ Tuesday, May 5, 2009 66

Django Test Utils • Mine! • Testmaker • Crawler • Random fanciness • http://github.com/ericholscher/django-test-utils/tree/ master Tuesday, May 5, 2009 67

Recording tests is generally seen as bad. Tuesday, May 5, 2009 68

My philosophy • Write tests. • Notice patterns and best practices • Automate recording of tests with those patterns • If you can’t automate, use tools to make it easier. Tuesday, May 5, 2009 69

Process for testmaker • Most view tests check status_code and response context • Write middleware that catches this info • Records it to a ﬁle • Err on the side of more data. Tuesday, May 5, 2009 70

Goals (That perfect world) Tuesday, May 5, 2009 71

Some form of TDD • Write tests as you write code • Makes your code easy to test Tuesday, May 5, 2009 72

Follow Django’s Model • Tests with every commit • Docs with every commit • Run tests before commiting Tuesday, May 5, 2009 73

Use a DVCS • At work we have a central SVN repo • Git feature branches • Code is staged for documentation and testing • Committed to SVN once it is “done” Tuesday, May 5, 2009 74

Continuous Integration Tuesday, May 5, 2009 75

NEVER LEAVE THE BUILD BROKEN Tuesday, May 5, 2009 76

Love Green Tuesday, May 5, 2009 77

Fast(er) Tests Tuesday, May 5, 2009 78

JSON Tuesday, May 5, 2009 79

Proﬁling python -m cProﬁle manage.py test Tuesday, May 5, 2009 80

Mock Objects http://www.voidspace.org.uk/python/mock/ Tuesday, May 5, 2009 81

Future and Ponies Tuesday, May 5, 2009 82

Summer of Code • Test-Only Models • Coverage • Windmill tests of the admin Tuesday, May 5, 2009 83

Test Suites in Django Tuesday, May 5, 2009 84

Central Testing Repository Tuesday, May 5, 2009 85

Nose Plugin Integration Tuesday, May 5, 2009 86

Things to remember • Testing is not hard, you just have to get started. • If your code doesn’t have tests, it will be hard/ impossible to refactor • Once you have tests, you need to run them! Tuesday, May 5, 2009 87

Credits • http://www.flickr.com/photos/tym/192416981/ • http://www.flickr.com/photos/seandreilinger/2459266781/ • http://www.homebabysafety.com/images/baby_crawl_suit.jpg • http://www.flickr.com/photos/pinkypigs/960572985/ Tuesday, May 5, 2009 88

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Django Testing

by ericholscher

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