Mocha

A test runner. It provides:

• Structure: describe, it
• Hooks: before, after
• Reporting pass/fail

/* global describe, it, beforeEach */
'use strict';

var SonicScrewdriver = require('./src/SonicScrewdriver');

describe('SonicScrewdriver', function() {

  describe('(constructor)', function() {

    it('Establishes a mental connection with the user', function() {
      // ** Test code goes here **
    });

    // ** More tests go here **

  });

  describe('#handleCommand()', function() {

    beforeEach(function() {
      // ** Setup that is run before each test in this group **
    });

    it('Responds to mental commands from the user', function() {
      // ** Mose test code goes here **
    });

    // ** More tests go here **

  });

});

Common Structure

• Class (or module name)
  • ::classMethod()
    • Test
    • Test
  • (constructor)
    • Test
    • Test
  • #instanceMethod()
    • Test
    • Test

Always place your before

and after functions in describe blocks.

Results

Chai

An assertion library. It provides:

• Styles: assert, expect, should
• Assertions:
  • .isTrue()
  • .equal()
  • .isArray()
  • .instanceOf()
  • .throws()

// Assert style

assert.equal(whoAmI, 'Groot', 'I am Groot');
 
assert.isTrue(teaServed, 'the tea has been served');
 
assert.instanceOf(chai, Tea, 'chai is an instance of tea');


// Expect style

expect(whoAmI).to.equal('Groot');
 
expect(teaServed).to.be.true;
 
expect(chai)to.be.an.instanceOf(Tea);


// Should style

whoAmI.should.equal('Groot');

teaServed.should.be.true;

chai.should.be.an.instanceOf(Tea);

Assertions/Expectations

• is true, false, null, undefined
• equality (shallow and deep)
• length
• above, below, within a range
• type or class identity
• has or inherited a property
• matches a regex
• throws an error

Sinon

Mocking library. Provides:

• spy()
• stub()
• mock()
• fake XHR

Use it to

• Isolate distinct functionality
• Remove dependencies on external code
• Provide predictable responses for
  internal or external interaction

Spies

• Track function calls
• Record arguments
• Record what is returned
• Record errors thrown
• Record the this value

• Can wrap an existing function
• Can fully intercept a function

Stubs

• Do everything a spy does
• Allow for pre-programmed responses
• Even different responses for certain args
• Can throw errors

Mocks

• Do everything spies and stubs do
• Provide build in expectations that can fail your test

Mocks are not generally needed.

It's often clearer to use Chai assertions with the spy tracking.

'use strict';

var chai = require('chai');
var sinon = require('sinon');
var SonicScrewdriver = require('./src/SonicScrewdriver');

var expect = chai.expect;

describe('SonicScrewdriver', function() {

  describe('(constructor)', function() {

    var testConnection = sinon.spy();
    var origGetConnection;

    before(function() {
      // Save the original getConnection functionality
      origGetConnection = SonicScrewdriver.getConnection;
    });

    beforeEach(function() {
      // Set up a fresh stub for the mental connection code
      SonicScrewdriver.getConnection = sinon.stub().returns(testConnection);
    });

    after(function() {
      // Restore the original getConnection functionality
      SonicScrewdriver.getConnection = origGetConnection;
    });

    it('Establishes a mental connection with the user', function() {
      var testScrewdriver = new SonicScrewdriver();

      expect(SonicScrewdriver.getConnection).to.have.been.called;
      expect(testScrewdriver._connection).to.equal(testConnection);
    });

  });

Fake XHR

• Intended for testing within a browser (or a PhantomJS environment)
• Replaces the built-in XMLHttpRequest, jQuery isn't touched
• Requests aren't actually sent
• You can log requests to a shared object
• You can send responses to each request, triggering callbacks

Fake XHR Setup

Checking Requests

// One Ajax request should be sent
expect(requests).to.have.length(1);

var request = requests[0];

// It should be hitting the screwdriver endpoint
expect(request.url).to.equal('/api/v1/screwdriver');

// It should be a POST request
expect(request.method).to.equal('POST');

// The body should contain a screwdriver id
expect(request.requestBody).to.contain('id=' + testScrewdriver.id);

Setting Responses

var request = requests[0];

var status = 200;
var headers = {'Content-Type': 'application/json'}
var body = JSON.stringify({'success': true});
request.respond(status, headers, body);