React-starter-kit: Problem async/await jest test

[ValSol]

const testAsync = () => Promise.resolve('hello world');

describe('async await test', () => {
  test('try 1', async () => {
    const result = await testAsync();
    expect(result).toBe('hello world');
  });
});

async await test
     encountered a declaration exception (5ms)

async await test › encountered a declaration exception

ReferenceError: regeneratorRuntime is not defined

    4  |   
    5  |   describe('async await test', () => {
  > 6  |   test('try 1', async () => {
    7  |     const result = await testAsync();
    8  |     expect(result).toBe('hello world');
    9  |   });

[ValSol]

Found a way:

In the file jest.config.js set:

setupFiles: ["<rootDir>/jest.setup.js"],

create new file jest.setup.js with this content:

import '@babel/polyfill';

Working!

[langpavel]

Hey, Thank you! Do you think that this should not be included?
New versions of node should support this seamplesly I believe :slightly_smiling_face:

[ValSol]

I used node version 8.9.4 on Windows 7 and had the problem. Generally, including polyfill makes available using any last ES6/ES7/ES8 semantic innovations in tests.

[langpavel]

you are running test with babel-node ?
regeneratorRuntime is used by babel. There is also babel-plugin-regenerator-runtime plugin which can inject this dependency automatically I believe..
Best will be to use simply node instead of babel-node
BTW most of new features are already supported in node 9, but node 8 have native support for most useful features too..

[ValSol]

I'm running test with node 8.9.4.
But you use babel/polyfill in webpack despite what feauteres support node.

[ValSol]

Figuring out how to make the webdriver.io + mocha work with RSK found another way for solution the issue. Instead of changing jest.config.js and adding jest.setup.js file we:

yarn add --dev @babel/[email protected] @babel/[email protected]

and insert this row:

plugins: [['@babel/plugin-transform-runtime', { polyfill: false }]],

in the .babelrc.js file

[zargold]

yes I too would prefer to not have to compile/use polyfills for my test suite Node v 10.0.0 I still get async

beforeEach(async () => {
                      ^
    SyntaxError: Unexpected token (

after using the above solution:

 PASS  __tests__/utils.js  // (test which has no async await)

 RUNS  __tests__/blocks.js
✨  Done in 5.44s.

so it seems to fail silently... but after a bit more research something is broken with one of the functions, but it fails silently and never tells me why (which is sad).