The document discusses test driven development (TDD) and how to apply it when building REST APIs with Node.js. It defines TDD as a process of writing unit tests before code, then writing minimal code to pass tests and refactoring code. Benefits include improved quality and reduced bugs, while limitations include an upfront time cost. Common pitfalls involve not running tests frequently, writing too many tests at once, or not maintaining the test suite. The document demonstrates building a REST API with Node.js using TDD with tools like Express, Mongoose, Mocha and Gulp.

1. REST API-LEVEL TDD WITH
NODEJS
Dang Viet Ha @ Tech Talk #2, Hanoi 2016

2. AGENDA
 What is TDD?
 The Benefits and Limitations of TDD
 Common Pitfalls of TDD
 REST-API TDD with Node.js
 Demo
 Question?

3. WHAT IS TDD?
 TDD: Test Driven Development refers to a style of programming
in which three activities are tightly interwoven
1. Coding
2. Testing (Unit Test)
3. Design (Refactoring)
 Basic Philosophy
1. write a "single" unit test describing an aspect of the program
2. run the test, which should fail because the program lacks that feature
3. write "just enough" code, the simplest possible, to make the test pass
4. "refactor" the code until it conforms to the simplicity criteria
5. repeat, "accumulating" unit tests over time

4. WHAT IS TDD?

5. THE BENEFITS AND LIMITATIONS
 Benefits
1. Writing tests first require you to really consider what you want from the code
2. Short feedback loop
3. Reduced time in rework
4. Less time spent in the debugger
5. Simplification & Loose Coupling (DI)
6. Improves quality and reduces bugs
 Limitations
1. Bigger up-front cost
2. Some codes are difficult to write the test.
3. Focus on micro-design not macro-design
4. Need to use mock to reproduce the real world.
5. Cannot cover all functional testing (UI, DB, Network,…)

6. COMMON PITFALLS
 Individual mistakes
1. Forgetting to run tests frequently
2. Writing too many tests at once
3. Writing tests that are too large or coarse-grained
4. Writing overly trivial tests, for instance omitting assertions
5. Writing tests for trivial code, for instance assessors
 Team pitfalls
1. Partial adoption - only a few developers on the team use TDD
2. Poor maintenance of the test suite - most commonly leading to a test suite
with a prohibitively long running time
3. Abandoned test suite (i.e. seldom or never run) - sometimes as a result of
poor maintenance, sometimes as a result of team turnover

7. REST-API TDD WITH NODE.JS
 REST-API: Express and Mongoose
 Authorization: Passport
 Dependencies Injection: Wagner
 Test framework: Mocha
 Validation & Assertion: Assert
 HTTP Request: Super-Agent
 Test And Watch task running: Gulp

8. REST-API

9. MOCHA

10. MOCHA

11. MOCHA

12. GULP TASK

13. DEMO

14. DEMO

15. DEMO

16. DEMO

17. DEMO

18. Q&A