Unit Testing in JavaScript Using Mocha & Chai

Presented at the Hill Country JavaScript Meetup - July 20, 2016

Transcript

1. WITH MOCHA + CHAI UNIT TESTING Hill Country JavaScript Meetup July 20, 2016
2. UNIT TESTING WITH MOCHA + CHAI QUESTIONS WE’LL ANSWER TONIGHT: ▸ Who does unit testing? ▸ What is unit testing? ▸ When should I use unit testing? ▸ Why do developers use unit testing? ▸ How do I get started with unit testing? 2
5. ERIC CARRAWAY MY PROGRAMMING BACKGROUND ▸ High School Computer Science in 1995 ▸ Borland Turbo Pascal ▸ 12 Year Gap ▸ Music School, Teaching Career ▸ Music Visualizations (2007) ▸ Self Study + Coding Bootcamp (2014) 5 Contact: eric@ericcarraway.com
8. AN ANALOGY LEARNING TO CODE 8
9. LEARNING TO CODE THREE-LEGGED STOOL ▸ Tutorials, step-by-step books ▸ codecademy.com ▸ Algorithm Challenges ▸ codingbat.com ▸ coderbyte.com ▸ Projects ▸ Ideation, Creativity 9
11. CONFIDENCE TO REFACTOR TEST-DRIVEN APPROACH 11
12. WE WANT MAKE A PACKAGE OF GOAL KILOS OF CHOCOLATE. WE HAVE SMALL BARS (1 KILO EACH) AND BIG BARS (5 KILOS EACH). RETURN THE NUMBER OF SMALL BARS TO USE, ASSUMING WE ALWAYS USE BIG BARS BEFORE SMALL BARS. RETURN -1 IF IT CAN'T BE DONE. Nick Parlante, CodingBat.com A FAVORITE ALGORITHM CHALLENGE 12
13. BACK TO JAVASCRIPT… 13
14. HTTPS://GITHUB.COM/ERICCARRAWAY/CODINGBAT-JS14
15. HOW DOES THIS RELATE TO TESTING? 15
16. ALGORITHM CHALLENGES ARE GENERALLY PURE-FUNCTIONS PURE-FUNCTIONS ARE A GREAT INTRODUCTION TO UNIT TESTING ▸ Tests that are only concerned with input and output of a function ▸ Focus narrowly before worrying about ▸ Dependency injection ▸ Global state ▸ Asynchronous behavior ▸ Mocks ▸ Browser automation 16
17. LEARN TO CODE IN THE BROWSER CODINGBAT.COM - INSTANT FEEDBACK ▸ We want make a package of goal kilos of chocolate. ▸ We have small bars (1 kilo each) ▸ and big bars (5 kilos each) ▸ Return the number of small bars to use, assuming we always use big bars before small bars ▸ Return -1 if it can't be done. 17
19. LIVE DEMO PRAGMATISM OF Q-UNIT HTTP://PLNKR.CO/EDIT/JNKDLO?P=PREVIEW MOCHA + CHAI BUT FIRST, 19
21. UNIT TESTING IN JAVASCRIPT QUICK REVIEW - BEFORE MOCHA + CHAI ▸ Who / What / When / Why / How ▸ Three-Legged Stool Analogy ▸ Algorithm Challenges (Test-Driven Approach) ▸ _____________________________________________________ ▸ Mocha + Chai ▸ Rock, Paper, Scissors ▸ Rock, Paper, Scissors, Lizard, Spock ▸ https://github.com/ericcarraway/codingbat-js/tree/master/ rockPaperScissorsLizardSpock 21
22. PREVIEW 22
23. GETTING SET UP ▸ mkdir mocha-chai-demo ▸ cd mocha-chai-demo ▸ npm install mocha ▸ npm install chai 23
25. GETTING SET UP FOR MOCHA + CHAI CREATE FILES AND DIRECTORIES 25
26. GETTING SET UP OPTIONS FOR FILE NAMES, DIRECTORIES ▸ Mocha, by default, looks for a directory called “test” ▸ this allows you to simply run `mocha` ▸ Another approach: `.spec` right next to your module 26
28. Live Coding Demo…