Alright I have a component called <TestButton />. Inside the <TestButton /> there are two Semantic UI React component, <Button /> and <Header>.  Basically, when the <Button> is clicked, it toggles display: none; to <H...

I am getting the following error whenever I run jest in commandline:   ? Test suite failed to run  /Users/<USER>/<Project>/src/login/LoginAPI.js:13         ...headers,         ^^^  SyntaxError: Unexpected token ...   The code that it brea...

class TestObject {   constructor(value) {     if (value === null || value === undefined) {       throw new Error('Expect a value!');     }   } }  describe('test the constructor', () => {   test('it works', () => {     ex...

I have an image upload endpoint in my API that accepts application/octet-stream requests and handles these streams. I'd like to write test coverage for this endpoint but cannot figure out how to use supertest to stream an image.  Here's my co...

I am using react-native init to create a react-native project. I am using https://github.com/andpor/react-native-sqlite-storage library for SQLite bindings.  I have a DbConnector.jest-test.js unit tests file. Contents are   import DbConnector from &#...

When writing unit tests with Jest. Why would you use beforeAll over simply assigning value straight to global variables or vice versa?  For example, what's the difference between the following two snippets?  Snippet 1  const mock = { key1: 'v...

Say I have the following module:  src/validators.js  export const isPositiveNumber = value => value > 0 && value < Number.MAX_SAFE_INTEGER;   I use it in another module:  src/calculators/volume.js  import { isPositiveNumber } from &#...

When I run Jest tests I get an error when it parses a file that contains an import with expose-loader:  index.js:  import 'expose-loader?PIXI!phaser-ce/build/custom/pixi';   And the error is:  Cannot find module 'expose-loader?PIXI!phaser...

I have a bunch of files that are configuring my Jest tests. I need them to specify environment for Puppeteer browser and setup/teardown behaviours.   module.exports = {    globalSetup: './jest-config/setup.js',    globalTeardown: './jest-...

I'm working within a Vagrant environment, which appears to leave some cached/metadata versions of files around, including tests.  So Jest will run both:  __tests__/myTest.spec.js __tests__/._myTest.spec.js   Turns out Jest offers a testRegex matc...