Unit Testing: The Why and The How

A basic introduction to reasons to do unit testing and basics of doing unit testing in PHPUnit.

Transcript

1. Unit Testing: The Why and The How Justin Yost Web Developer at Loadsys 1 CC BY-NC 4.0 Justin Yost
2. Unit Testing Tests for the smallest possible unit of code. 2 CC BY-NC 4.0 Justin Yost
3. Unit Testing Firstly there is a notion that unit tests are low-level, focusing on a small part of the software system. Secondly unit tests are usually written these days by the programmers themselves using their regular tools - the only difference being the use of some sort of unit testing framework. Thirdly unit tests are expected to be significantly faster than other kinds of tests. — Martin Fowler 3 CC BY-NC 4.0 Justin Yost
4. Unit Testing • Test and verify the intent and design of units of code, typically at the function/method level in PHP and C type languages. • Unit tests are written in the same language you write your code in (though you may include a test framework). • Should be fast, they shouldn't slow down your process for writing code. 4 CC BY-NC 4.0 Justin Yost
5. Unit Testing Goals • Verify implementation of code matches the programmer's intent. • Verify bugs are solved today and in the future (Regressions). • Create better designed software. • Improve Refactoring 5 CC BY-NC 4.0 Justin Yost
6. Why Unit Testing • Can't I just manually test stuff? • Isn't unit testing going to slow me down? • No one cares? • Business/Manager/Client/etc won't let me spend time on this stuff. 6 CC BY-NC 4.0 Justin Yost
7. Complaint: Manually Test • Slow • You write code not hitting refresh • Computers do repetitive stuff really well • You forget • You make mistakes • You are bad at remembering what you tested • You are bad at communicating needed tests to other co-workers 7 CC BY-NC 4.0 Justin Yost
8. Complaint: Unit Testing is Slow • Unit Testing is overall faster • It may be slower in terms of pure speed to develop a thing • Total Time to a reliable useful product is slower 8 CC BY-NC 4.0 Justin Yost
9. Research The results of the case studies indicate that the pre-release defect density of the four products decreased between 40% and 90% relative to similar projects that did not use the TDD practice. Subjectively, the teams experienced a 15–35% increase in initial development time after adopting TDD. — Realizing quality improvement through test driven development: results and experiences of four industrial teams http:/ /research.microsoft.com/en-us/groups/ese/nagappan_tdd.pdf 9 CC BY-NC 4.0 Justin Yost
10. Complaint: Unit Testing is Slow • Unit Testing may be slower in the initial learning, phase, so is the new framework, so is the new language, so is everything • The speed improvements in the long run will be worth it • The short improvements in loss of defects will easily be worth it 10 CC BY-NC 4.0 Justin Yost
11. Complaint: Unit Testing is Slow • What about for an MVP? 11 CC BY-NC 4.0 Justin Yost
12. Then you just have MP. — Andrew Lechowicz https:/ /twitter.com/alecho_/status/ 704023025046462464 12 CC BY-NC 4.0 Justin Yost
13. Complaint: Who Cares? • Your customers care about quality • Your boss/manager should care about quality 13 CC BY-NC 4.0 Justin Yost
14. Complaint: Who Cares? • Unit testing isn't just fixing bugs that you observe • It's about preventing bugs in the first place 14 CC BY-NC 4.0 Justin Yost
15. Complaint: No Time • Microsoft Research • If you have limited time then you should care even more, for any bugs are detrimental to your time 15 CC BY-NC 4.0 Justin Yost
16. General Theory of Unit Testing • Unit Testing is writing code that proves what you did works • Unit Testing means you stay in the flow of the code you are working on longer • Unit Testing means you spend less time debugging and figuring out what went wrong • Unit Testing means you spend time thinking through your code 16 CC BY-NC 4.0 Justin Yost
17. General Theory of Unit Testing • None of these may be perfect • None of these may the right answer • You should do it because you care about producing quality software • If you don't learn now, what happens when you really need it? 17 CC BY-NC 4.0 Justin Yost
18. The Why • It is faster • It produces a better quality product • It will make you a better developer/engineer 18 CC BY-NC 4.0 Justin Yost
19. The How 19 CC BY-NC 4.0 Justin Yost
20. PHPUnit • A framework for writing unit tests • Frameworks may have their own customizations 20 CC BY-NC 4.0 Justin Yost
21. PHPUnit Install • Phar wget https://phar.phpunit.de/phpunit.phar chmod +x phpunit.phar sudo mv phpunit.phar /usr/local/bin/phpunit 21 CC BY-NC 4.0 Justin Yost
22. PHPUnit Install • Composer composer require --dev phpunit/phpunit 22 CC BY-NC 4.0 Justin Yost
23. Test Pattern • Arrange • Act • Assert 23 CC BY-NC 4.0 Justin Yost
24. Code Time 24 CC BY-NC 4.0 Justin Yost
25. Other Resources on Unit Testing? • Grumpy Programmer: Chris Hartjes - https:/ /grumpy-learning.com/ • PHPUnit: https:/ /phpunit.de/ 25 CC BY-NC 4.0 Justin Yost
26. Questions? • twitter.com/jtyost2 • github.com/jtyost2 • justinyost.com • lynda.com/justinyost 26 CC BY-NC 4.0 Justin Yost