Front End Testing With Jest

• Jest | Painless Javascript Testing
• Instulation
• Setup
• Execution

Jest

Painless JavaScript Unit Testing built on top of the Jasmine test framework.

• Familiar Approach: Built on top of the Jasmine test framework, using familiar expect(value).toBe(other) assertions

• Mock by Default: Automatically mocks CommonJS modules returned by require(), making most existing code testable

• Short Feedback Loop: DOM APIs are mocked and tests run in parallel via a small node.js command line utility

Instulation

Note: You will use npm to install Jest. If you don't have npm you can get it by installing node.js which includes npm.

To install Jest:

1. Run $ npm install jest-cli --save-dev
2. Add the following to the package.json file.

{
 ...
 "scripts": {
   "test": "jest"
 }
 ...
}

Setup

1. Create a directory __tests__/.

• This is where you will keep your individual tests.

Execution

1. Run npm test

• You should see a result similar to this:
  [PASS] __tests__/name-of-your-test.js (0.015s)

Resources

• https://facebook.github.io/jest/ Jest website
• http://facebook.github.io/react/docs/test-utils.html Test Utilities explained
• https://github.com/securingsincity/react-jest-example A React/Jest examples.
• http://jasmine.github.io/ Jasmine website.