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Hooks In Mocha

Introduction

In this article, we will look at what are the different hooks available in Mocha Test Framework.

Before deep diving into hooks let us look at what is mocha

  • Mocha is a javascript test framework that runs on node.js. It makes us write simple asynchronous test.
  • Mocha tests are written using describe and it blocks.

To install mocha use the below command,

  1. Describe blocks defines the Test Suite
  2. it block defines a Test case.
 describe('test suite name', function () {
    it('test case name', async ()=> {
      //test code to implemented
    });
  });
 

Hooks

Hooks are the preconditions and the postconditions that runs before and after your tests.

Below are the inbuilt BDD hooks available in mocha

Behavior Driven Development is a software development approach that allows the tester/business analyst to create test cases in simple text language (English).

  • before Hook
    Runs once before the all tests(i.e it blocks) in the suite.see
    Example
    Creating instance of the browser before all the test cases execute
  • after Hook
    Runs once after the tests (i.e it blocks) in the suite.
    Example
    Close all the instance of the browser after all the test cases execute
  • beforeeach Hook
    Runs before each test(i.e it block) in the suite
    Example
    Connect to the database/ to get the require data to pass on the test cases /call a utility function before a test case run.
  • aftereach Hook
    Runs after each test(i.e it block) in the suite
    Example
    close the database connection which was opened.
describe('hooks', function() {
    before(function() {
        console.log('inside before hook')
    });
    after(function() {
        console.log('inside after hook')
    });
    beforeEach(function() {
        console.log('inside beforeeach hook')
    });
    afterEach(function() {
        console.log('inside aftereach hook')
    });
    // test cases
    it('testcase', function() {
        console.log('inside test block')
    });
});

Output after execution will be,

  • inside before hook
  • inside beforeeach hook
  • inside test block
  • inside aftereach hook
  • inside after hook

Note
Depending upon the no of test cases in your suite, the beforeach and aftereach block runs will run that many times

Ex: if there are two test cases then the output will be

  • inside before hook
  • inside beforeeach hook
  • inside testcase block
  • inside aftereach hook
  • inside beforeeach hook
  • inside second test case block
  • inside aftereach hook
  • inside after hook

TDD Hooks

TDD stands for Test Driven Development.

Test Driven Development (TDD) is a software development approach in which test cases are developed to specify and validate what the code will do.

Test Cases for each functionality are created and tested first and if the test fails then the new code is written in order to pass the test.

The below are available hooks for TDD in mocha,

  • suite() - Test group
  • test() - Helps to create Individual test
  • setup() - setup function called before each test.
  • teardown() - teardown function called after each test
  • suiteSetup() - suiteSetup fucntion called before all tests in the suite
  • suiteTeardown() - suiteTeardown function called after all tests in the suite

In order to use this tdd hooks in mocha, we need to import the hooks from mocha modules

const {suite,test,setup,teardown,suiteSetup,suiteTeardown}=require('mocha')

Usage

import {suite,test,setup,teardown,suiteSetup,suiteTeardown} from 'mocha'
suite('TDD hooks', () => {
    suiteSetup(() => {
        console.log('one suitesetup')
    });
    suiteTeardown(() => {
        console.log('one suiteteardown')
    });
    setup(() => {
        console.log('one setup')
    });
    teardown(() => {
        console.log('one teardown')
    });
    // test cases
    test('testcases', () => {
        console.log('one test')
    });
});

Output after execution will be,

  • one suitesetup
  • one setup
  • one test
  • one teardown
  • one suiteteardown

Note
Depending upon the number of test cases in your suite, the setup and teardown block runs will run that many times

Ex

If there are two test cases then the output will be,

  • one suitesetup
  • one setup
  • one test
  • one teardown
  • one setup
  • second test
  • one teardown
  • one suiteteardown

Summary

Hope this article was interesting in learning the different hooks available in Mocha Test Automation Framework. Hope this will be helpful while writing Test Automation scripts.


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