Unit testing yer javascripts

Fresno.js Javascript User Group

Greg Goforth
06-07-16

Director of Development - Bitwise Industries

Title Text

WHY???

• Give developers confidence in the code they are writing
   
• Ensures future code changes don't change what's expected of the code
   
• Documents how code should be interacted with
   
• Helps to know if anything is broken before deployment...aka continuous integration

Continuous Integration

• Like having someone always watching over your shoulder for misplaced commas and periods...
   
• Automate the running of your tests
   
• Platforms like Travis, Circle and Codeship

What to test???

• A unit can be anything really, but usually no larger than a single function
   
• Single responsibility functions are easier to test
   
• Functions that don't rely on outside dependencies are easier to test.

Should I be testing EVERYTHING?

• Most product shops tend to have robust testing suites.
   
• Smaller app development shops tend to not test as much due to added overhead and longer development timelines.
   
• (IMO) Execs care less about Unit Tests and more about shipping.
   
• Find a sweet spot, test mission critical pieces.

INCOMING OPINION SLIDE

When should I unit test?

• In the beginning, having a product is more important than a test suite. (insert audible gasp)
   
• Once you achieve an MVP (minimum viable product) it might be a good time to determine what needs testing.
   
• You have no users.  Unit tests don't get you more users, they can only help you keep them.
   
• All of the above will be highly contested by the next guy you talk to about unit testing.

The Testing Stack

Karma

• Responsible for running tests
• Developed by google, works well for testing angular apps (and others)
• Requires the user of assertion library (jasmine, mocha / chai) .  

Jasmine

• Jasmine tests are referred to as a specs.
• Provides functions like describe, it, and expect.
• Structures tests in such a way that other developers can understand what's going on .

A simple test...

describe("The addOne function", function() {
  it("should add one to any number", function() {
    expect(addOne(4).toEqual(5);
  });
});

You can almost read it in plain english...

"The addOne function should add one to any number"

The setup...

• Install Karma per - http://goo.gl/mXRoCl
   
• Install Jasmine - npm install jasmine -g
   
• Install Chrome (required to run the tests in a browser environment)
   
• karma init
   
• karma start

Lets write and test the addOne function.