mocha

What is mocha?

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.

What are mocha's main functionalities?

Test Organization

Organize tests in suites and sub-suites using describe() and context(), and specify test cases using it().

"use strict";\nconst assert = require('assert');\ndescribe('Array', function() {\n  describe('#indexOf()', function() {\n    it('should return -1 when the value is not present', function() {\n      assert.equal([1, 2, 3].indexOf(4), -1);\n    });\n  });\n});

Asynchronous Testing

Support for testing asynchronous code with ease, using callbacks, promises, or async/await.

"use strict";\nconst assert = require('assert');\ndescribe('User', function() {\n  describe('#save()', function() {\n    it('should save without error', function(done) {\n      const user = new User('Luna');\n      user.save(function(err) {\n        if (err) done(err);\n        else done();\n      });\n    });\n  });\n});

Hooks

Lifecycle hooks such as before(), after(), beforeEach(), and afterEach() for setting up preconditions and clean-up after tests.

"use strict";\ndescribe('Connection', function() {\n  before(function() {\n    // runs once before the first test in this block\n  });\n\n  after(function() {\n    // runs once after the last test in this block\n  });\n\n  beforeEach(function() {\n    // runs before each test in this block\n  });\n\n  afterEach(function() {\n    // runs after each test in this block\n  });\n\n  // test cases\n});

Other packages similar to mocha

jest

Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It works out of the box for any React project and is often compared to Mocha for its comprehensive feature set including a built-in assertion library and mock functions.

jasmine

Jasmine is a behavior-driven development framework for testing JavaScript code. It does not rely on browsers, DOM, or any JavaScript framework. Thus, it's suited for websites, Node.js projects, or anywhere that JavaScript can run. It's compared to Mocha for its clean syntax and testing capabilities.

ava

AVA is a test runner for Node.js with a concise API, detailed error output, and process isolation that lets you develop with confidence. It is often compared to Mocha for its modern, concurrent testing features, but differs in its approach to running tests in parallel by default.