Unit testing involves testing small isolated parts of code, such as functions or classes. Test-driven development (TDD) is a methodology where you write unit tests before writing the code itself to drive the development. TDD follows a cycle of red, green, refactor - writing a test that fails, making it pass, then refactoring code. TDD can improve code quality but requires understanding the technology and takes more time initially.

1. TDD IN JAVASCRIPTTDD IN JAVASCRIPT

2. Name: Yoan Ribeiro
Title: Full-Time Learner
Works @ JS-Republic
@yoanribeiro Yoanribeiro

3. SUMMARYSUMMARY
Unit Testing
The concept
Demo
Pros/cons

4. TDDTDD == UNIT TESTINGUNIT TESTING
You make unit test by using TDD but make
unit test is not necessary using TDD

5. UNIT TESTINGUNIT TESTING
when you test a small part of code isolated
from the rest.
(e.g. function or class)

6. UNIT TESTING - RULESUNIT TESTING - RULES
AUTOMATIC
VERY FAST (<300ms)
ISOLATED (no side effect)
VERIFY A SMALL UNIT

7. Take, the example of a function responsible of returning the
number of specific dom elements.
We will use Mocha as test runner
Chai as assertion library
UNIT TESTING - JS FLAVOR EXAMPLEUNIT TESTING - JS FLAVOR EXAMPLE

8. UNIT TESTING - JS FLAVOR EXAMPLEUNIT TESTING - JS FLAVOR EXAMPLE

9. REMEMBER :REMEMBER : GIVENGIVEN WHEN THEN WHEN THEN
Prepare the case you want to test

10. REMEMBER :REMEMBER : GIVEN GIVEN WHENWHEN THEN THEN
Call what you want to test

11. REMEMBER : GIVEN WHEN REMEMBER : GIVEN WHEN THENTHEN
Verify the behavior, result of what you test

12. REMEMBER : GIVEN WHEN THENREMEMBER : GIVEN WHEN THEN
The three parts of every unit test

13. TTESTEST DDRIVENRIVEN DDEVELOPMENTEVELOPMENT
First test your use case, then implement your
use case, refactor and start over until
functionality is over.

14. TDD, AN OLD STORYTDD, AN OLD STORY
19571957 - DIGITAL COMPUTER PROGRAMMING,- DIGITAL COMPUTER PROGRAMMING, D.D.MCCRACKEND.D.MCCRACKEN
19681968 - REPORT OF THE NATO SOFTWARE ENGINEERING CONFERENCE,- REPORT OF THE NATO SOFTWARE ENGINEERING CONFERENCE, P.NAURP.NAUR
19721972 - THE HUMBLE PROGRAMMER,- THE HUMBLE PROGRAMMER, EDSGERW.DIJKSTRAEDSGERW.DIJKSTRA
20002000 - TEST-DRIVEN DEVELOPMENT BY EXAMPLE , - TEST-DRIVEN DEVELOPMENT BY EXAMPLE , KENTBECKKENTBECK

15. TDD IS A METHODOLOGYTDD IS A METHODOLOGY

16. TDDTDD == WRITEWRITE ALLALL YOUR TESTS FIRSTYOUR TESTS FIRST

17. TDD IS A CYCLETDD IS A CYCLE

18. REDRED
GREENGREEN
REFACTORREFACTOR

19. REDRED / GREEN / REFACTOR/ GREEN / REFACTOR
Write a test
which fails
Refactor by
keeping it
green
Make the test
pass
Write a unit test which
test a case not yet
implemented. Obviously,
this test will failed !
It's what we want

20. REDRED // GREENGREEN / REFACTOR/ REFACTOR
Write a test
which fails
Refactor by
keeping it
green
Make the test
pass
Write an implementation
which resolve the case
that you just test (and
the previous test cases)
and no more

21. REDRED / GREEN // GREEN / REFACTORREFACTOR
Write a test
which fails
Refactor by
keeping it
green
Make the test
pass
Refactor to improve the
general implementation
by keeping every use
case green.

22. RED / GREEN / REFACTORRED / GREEN / REFACTOR
Write a test
which fails
Refactor by
keeping it
green
Make the test
pass

23. DEMODEMO

24. PROSPROS
Better code coverage
Better architecture (less coupling)
Gives us a degree of certainty

25. CONSCONS
Require good understanding of the used technology
Can be a little bit time consuming at the beginning

26. CONCLUSIONCONCLUSION
TDD is nice to increase quality
TDD should not be a dogma
To make unit tests every single
time is already good thing

27. HTTPS://GITHUB.COM/YOANRIBEIRO/TDD-JS-STAR-APRILHTTPS://GITHUB.COM/YOANRIBEIRO/TDD-JS-STAR-APRIL

28. TITLE TEXTTITLE TEXT