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Explain Mocha's testing framework - describe(), it() and before()/etc hooks
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| // # 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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beforeEach, runs before each test in this block, that is, run before every it() in this block.