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Forked from samwize/mocha-guide-to-testing.js
Created April 26, 2017 18:05
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Explain Mocha's testing framework - describe(), it() and before()/etc hooks
// # Mocha Guide to Testing
// Objective is to explain describe(), it(), and before()/etc hooks
// 1. `describe()` is merely for grouping, which you can nest as deep
// 2. `it()` is a test case
// 3. `before()`, `beforeEach()`, `after()`, `afterEach()` are hooks to run
// before/after first/each it() or describe().
//
// Which means, `before()` is run before first it()/describe()
// -----------------------------------------------------------------------------
// should.js is the preferred assertion library
var should = require('should');
// **Only 1 test case (in a nameless test suite)**
it('birds should fly', function(){
/** here.should.be.tested
* However, as long as no error within a it(),
* it() is considered PASSED */
})
// **Only 1 test case, but nested 3-level deep**
// describe() are:
// - commonly known as test suites, which contains test cases
// - merely groups, and you can have groups within groups
describe('galaxy', function(){
describe('earth', function(){
describe('singapre', function(){
it('birds should fly', function(){ /** ... */ })
})
})
})
// **2 test cases in 1 test suite**
// A common scenario.
describe('singapre', function(){
it('birds should fly', function(){ /** ... */ })
it('horse should gallop', function(){ /** ... */ })
})
// **Run once before the first test case**
describe('singapre', function(){
before(function(){
console.log('see.. this function is run ONCE only')
})
it('birds should fly', function(){ /** ... */ })
it('horse should gallop', function(){ /** ... */ })
})
// **Run once before each test case**
describe('singapre', function(){
beforeEach(function(){
console.log('see.. this function is run EACH time')
})
it('birds should fly', function(){ /** ... */ })
it('horse should gallop', function(){ /** ... */ })
})
// **2 test suites in a big test suite**
// A common scenario.
describe('earth', function(){
describe('singapre', function(){
it('birds should fly', function(){ /** ... */ })
})
describe('malaysia', function(){
it('birds should soar', function(){ /** ... */ })
})
})
// **before() can be applied to describe() too**
describe('earth', function(){
before(function(){
console.log('see.. this function is run ONCE only, before first describe()')
})
describe('singapre', function(){
it('birds should fly', function(){ /** ... */ })
})
describe('malaysia', function(){
it('birds should soar', function(){ /** ... */ })
})
})
// **beforeEach() can be applied to describe() too**
describe('earth', function(){
beforeEach(function(){
console.log('see.. this function is run EACH time, before each describe()')
})
describe('singapre', function(){
it('birds should fly', function(){ /** ... */ })
})
describe('malaysia', function(){
it('birds should soar', function(){ /** ... */ })
})
})
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