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JavaScript BDD with Jasmine

Objectives

  1. Experience some of the differences between clean/good and unclean/bad JS
  2. Learn Jasmine as a tool to help you write BDD JS specs

Good JS vs. Bad JS

JavaScript: The Good Parts

Why you should care:

Less bugs

Bad js is at times very hard to debug

Maintainable code

  • Don't leave unused variables dangling in the wind
  • Don't use a variable without defining it first with the var keyword
  • Don't use == when you should use ===
  • Don't make two libraries override each others' functionality by putting crap in global scope
  • Keep your cyclomatic complexity down to a minimum
  • Have your functions do one thing well
  • Don't write assignments in ifand for equality checks
  • Don't assume braces

Lower blood pressure

Happier team members

All of the above is hard to keep track of manually

Use a tool: JSHint

About JSHint

Exercise: take some js you've written, and dump it into JSHint

Let's add JSHint to Sublime

Sublime Package Control

Forllow the Simple section of the installation instructions here: Sublime Package Control Installation Instructions

JSHint Gutter

CRUCIAL: First, run node -v in your terminal. This should output the version of node on your machine. If you don't have nodejs installed:

  • ON MAC: In your terminal, run this: brew install node
  • ON LINUX: In your terminal, run this: apt-get install nodejs

Follow the Sublime Package Manager section of the instructions here: JSHint Gutter Installation Instructions

  • If you have Sublime Text 3:, enable Automatically linting on edit or save
  • If you have Sublime Text 2, enable Automatically linting on save

Exercise: Write some js code in Sublime and play with JSHint

JS BDD Testing with Jasmine

Together: name some reasons why we should test our code

Basic Jasmine syntax

It's like RSpec, but with JS

In RSpec, what 2 arguments do the describe, it methods take?

Like in RSpec with ruby, in Jasmine with JS, which is based on RSpec, describe and it are functions that are applied to/take two arguments. With RSpec, the second argument is a block; with Jasmine, the second argument is an anonymous function.

A test suite begins with describe, with two parameters:

  • A string giving the test suite a name
  • An anonymous function that implements the test suite

Together: Let's take a look at a test suite that I had begun to write

Iterators Test Suite

Exercise: Complete the test suite and implementation

Your resources for today:

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