The Testing Goat

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TDD for the Web, with Python, Selenium, Django, JavaScript and pals...

"TDD / Django tutorial: The Book!"

Sun 03 March 2013
By Harry

[update April 2012] : The book is now coming out on O'Reilly! more info here:

Thanks so much for following on this far! I'm afraid that's all there is for now, but I am about to start on the next stage -- a proper book on TDD for web apps.

If you've found the tutorial useful so far, I wonder whether I can solicit some feeback regarding a book version?

Here's the chapter outline I've got so far. Now, remember, this is a very rough draft, and it's very much bound to change, but I'd love to hear your thoughts... Especially about some quite general questions, like:

  • Am I broadly covering the right sort of stuff?
  • Am I right to spend plenty of time talking about JavaScript, as well as Python?
  • What should I choose as my example app? I've written the outline as if it were a forums app, but I'm starting to see the appeal of one of the other classic examples, the "to-do list" (very simple at base, can be extended easily, opportunities for sharing/social bits, plenty of stuff to do on the client-side too...). What would you choose as an example?

PART 1 - Beginning web app development with TDD

The idea is to dive straight in with a practical example, rather than talking a lot of theory up-front. I had originally thought to start with a toy example (cf these 3 abandoned chapters: ), but I decided that people prefer real practical stuff to toy examples...

I also want the first few chapters to be very short + bit-sized, so that the reader feels like they're really making progress quickly... (the inspiration comes from Kent Beck's TDD by Example, an awesome book)

Essentially part 1 is a re-hash of this online tutorial, using a differnt example app...

1: Our first functional test with Selenium

  • Briefly discuss difference between functional testing (AKA acceptance testing, integration testing, whatever) and unit testing
  • Write first test - Introduce Selenium, setUp, tearDown
  • Demonstrate we can get it to open a web browser, and navigate to a web page eg -

2: Getting Django set-up and running

  • Change our test to look for the test server
  • Switch to Django LiveServerTestCase. Explain
  • Get the first test running and failing for a sensible reason
  • Create django project startproject
  • It worked!

3: A static front page

  • Look for "Welcome to the Forums", or similar
  •, direct_to_template ?

4: Super-users and the Django admin site

  • Extend FT to try and log in
  • Explain the admin site
  • Database setup,, syncdb,
  • runserver to show login code
  • Explain difference between test database and real database
  • Fixtures

5: First unit tests and Database model

  • Distinction between unit tests and functional tests
  • Extend FT to try and create a new topic
  • new app
  • test/code cycle

6: Testing a view

  • again
  • Test view as a function
  • assert on string contents

7: Django's template system

  • Introduce template syntax
  • Keep testing as a function
  • The, introduce the Django Test Client

8: Reflections: what to test, what not to test

  • time for a bit of theory/philosophy
  • "Don't test constants"
  • Test logic
  • Tests for simple stuff should be simple, so not much effort

9: Simple Forms

  • Manually coded HTML
  • Refactor test classes

10: User Authentication

  • Sign up, login/logout
  • Email?

11: More advanced forms

  • Use Django Forms classes

12: On Refactoring

  • Martin Fowler
  • Tests critical
  • Methodical process - explain step by step

PART 2: More advanced testing for a more advanced site

14: Notifications

  • Django Notifications, for post edits

15: Adding style with MarkDown

  • Using an external library

16: Switching to OAuth: Mocking

  • "Don't store passwords"
  • Discuss challenges of external dependencies

17: Getting Dynamic: Testing Javascript part 1

  • Simple input validation
  • Choose JS unit testing framework (probably Qunit, or YUI)

18: Testing Javascript part 2 - Ajax

  • Dynamic previews of post input

19: Getting pretty: Bootstrap

  • Bring in nicer UI elements

20: Getting pretty: Gravatar

  • pictures for users

PART 3: Getting seriously sexy

21: Getting serious about the client-side + single-page website?

  • Introduce one of the client-side js frameworks -- backbone.js / ember.js / angular

22: Switching Databases 1: PostgreSQL

  • show how Django makes this easy

23: Websockets and Async on the server-side

  • we want dynamic notifications of when new posts appear on a thread we're looking at
  • Need to spin up, Tornado/Twisted/Gevent as well as Django LiveServerTestCase
  • FT opens multiple browser tabs in parallel
  • Big change!

24: Switching Databases 2: NoSQL and MongoDB

  • obligatory discussion of NoSQL and MongoDB
  • descrine installation, particularities of testing

26: Continuous Integration

  • Need to build 3 server types
  • Jenkins (or maybe buildbot)
  • Need to adapt Fts, maybe rely less on LiveServerTestCase

27: Caching for screamingly fast performance

  • unit testing memcached
  • Functionally testing performance
  • Apache ab testing

Well, that's what I have so far. What do you think? Have I missed anything out? Does anything seem superfluous? Most importantly, would you buy it?


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A selection of links and videos about TDD, not necessarily all mine, eg this tutorial at PyCon 2013, how to motivate coworkers to write unit tests, thoughts on Django's test tools, London-style TDD and more.

Old TDD / Django Tutorial

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