Taming big balls of mud with functional tests

Big balls of mud are software systems with poor architecture due to business pressure, developer turnover and compounding technical debt.

Using a fully fledged web application written using Django/Celery/Postgres/Redis/Cron that sends email reminders as an example, I will show the audience how they can easily write realistic test cases and do test driven development with a new testing framework, making refactoring such code easier.

Hitch is a loosely coupled, isolated open source testing framework, with a strong emphasis on functional testing. It orchestrates interacting services and enacts scenarios in isolated tests that can't easily be scripted without it (for instance, with Django's LiveServerTestCase).

These tests will involve installing a Django app in a virtualenv, interaction using a browser with selenium, mocking the passage of time, sending emails and more.

Transcript

1. Taming big balls of mud with functional tests Colm O’Connor
2. What IS a ball of mud?
4. Model
5. Model View
6. Model View Controller
7. Model View Controller
8. Model View Controller Another model
9. Model View Controller Another model Repeated model
10. Model View Controller Another model Repeated code Repeated model
11. Model View Controller Another model Repeated code Repeated model More repeated code
12. Model View Controller Another model Hack Repeated code Repeated model More repeated code
13. Model View Controller Another model Hack Repeated code Repeated model More repeated code Bad hack
14. Model View Controller Another model Hack Repeated code Repeated model More repeated code Bad hack Worse hack
15. Model View Controller Another model Hack Repeated code Repeated model More repeated code Bad hack Worse hack OMG
16. Model View Controller Another model Hack Repeated code Repeated model More repeated code Yuck Bad hack Worse hack OMG
17. Model View Controller Another model Hack Repeated code Repeated model More repeated code Yuck Disgusting Bad hack Worse hack OMG
18. Model View Controller Another model Hack Repeated code Repeated model More repeated code Yuck Disgusting Bad hack Worse hack OMG OMFG!!
19. Model View Controller Another model Hack Repeated code Repeated model More repeated code Yuck Disgusting Bad hack Worse hack OMG OMFG!! OMFGWTFBBQ!
20. What IS a ball of mud?
21. What IS a ball of mud? • Repetitive code • Tightly coupled code
22. Tightly coupled code? • The degree to which individual modules are dependent upon one another’s implementation.
23. Tightly coupled code? • The degree to which individual modules are dependent upon one another’s implementation. • Degree of ease with which you can swap one module out with another.
24. Refactoring
25. Refactoring
26. Tests! Unit test? Functional test?
27. What do we do next? Unit test? Functional test?
28. What do we do next? Unit test? Functional test?
29. Unit tests ?
30. Unit tests ? ?
31. Unit tests ? ? ?
32. Example code def horrible_method(like, fifty arguments): [ lots of ugly crap ] def nice_method(a couple or three args): [ only nice things here ] ???
34. • The more tightly coupled your code, the more necessary tests become to ascertain that nothing broke when you refactor it.
35. • The more tightly coupled your code, the more necessary tests become to ascertain that nothing broke when you refactor it. • ...and the more useless unit tests become at helping you do that.
36. • The more tightly coupled your code, the more necessary tests become to ascertain that nothing broke when you refactor it. • ...and the more useless unit tests become at helping you do that.
37. A real functional test Let’s see some code sudo pip install hitch
43. Test
44. - engine: engine.py:DjangoReminderTestExecutionEngine name: Sign up, create reminder and wait for email reminder to arrive in python preconditions: python_version: 2.7 scenario: - Load website - Click: register - Fill form: id_username: django id_email: django@reinhardt.com id_password1: jazzguitar id_password2: jazzguitar - Click submit - Click: create - Fill form: id_description: Remind me about upcoming gig. id_when: 30 days - Click: create - Wait for email: Containing: Confirm E-mail Address - Confirm emails sent: 1 - Time travel: Days: 30 - Wait for email: Containing: Remind me about upcoming gig.
46. Try it out: Prerequisites Ubuntu: $ sudo apt-get install python python- virtualenv python-pip postgresql redis-server git firefox node-less automake libtool Mac OS: $ brew install python redis postgresql git libtool automake npm $ npm install -g less $ pip install -U setuptools pip virtualenv
47. Try it out $ sudo pip install hitch / pipsi install hitch $ git clone https://github.com/hitchtest/django-remindme.git $ cd django-remindme/ $ git clone https://github.com/hitchtest/django-remindme-tests.git $ cd django-remindme-tests/ $ hitch init $ hitch test simple_reminder.test - OR - $ hitch test simple_reminder.test --settings macos.yml
48. Django is just the start • Hitch is an ongoing project. • It can test more than just Django. • It can test more than just Python. • Very simple to develop a service wrapper.
49. Thank you http://www.hitchtest.com/ Try:https://github.com/hitchtest/django-remindme-tests/ Twitter: @testhitch Reddit: /r/hitchtest pip install hitch