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Known Errors

TypeError: Reflect.hasOwnMetadata is not a function​

$ jest compatible.test
 FAIL  src/components/Layout/components/compatible.test.tsx
  ● Test suite failed to run

    TypeError: Reflect.hasOwnMetadata is not a function

      at ../../node_modules/inversify/src/annotation/injectable.ts:7:17

Solution:

Include import 'reflect-metadata'; at the top of the test file.

ESM files need to be added to transformation​

$ jest compatible.test
 FAIL  src/components/Layout/components/compatible.test.tsx
  ● Test suite failed to run

    Jest encountered an unexpected token

    This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.

    By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/en/ecmascript-modules for how to enable it.
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/en/configuration.html

    Details:

    /Users/veeramarni/Documents/development/workspace/projects/IDE/admin-layout/node_modules/@adminide-stack/user-auth0-client/lib/index.js:1

Solution:

Jest throws error when esm files are used. They need to be added to transformIgnorePatterns in jest.config.js file.

For example

    transformIgnorePatterns: [
        '/node_modules/(?!(@vscode-alt/monaco-editor|@files-stack/server-core|@adminide-stack/platform-browser|@adminide-stack/platform-client|abortable-rx|@adminide-stack/user-auth0-client|lodash-es|react-dnd-html5-backend|react-sortable-tree|react-dnd|dnd-core)/).+\\.js$',
    ],

Envalid need the required env variables to be available​

$ jest compatible.test
  ●  process.exit called with "1"

      at defaultReporter (../../node_modules/envalid/src/reporter.ts:67:13

Solution:

Test cases also need to have environment variables available when you using a package that uses envalid.

// make sure `processe.env.ENV_FILE` points 
// to `config/test/test.env` and file should exist.

// package.json will have script for 
// `"test": "cross-env ENV_FILE=../../config/test/test.env jest",`

require('dotenv').config({ path: process.env.ENV_FILE });

Cannot read property 'child' of undefined on React 17​

 TypeError: Cannot read property 'child' of undefined

      25 | 
      26 | 
    > 27 | const wrapper = mount(
         |                 ^
      28 |     <Provider store={ store } >
      29 |         <DeleteEventFab />
      30 |     </Provider>

      at getFiber (node_modules/enzyme-adapter-react-16/src/detectFiberTags.js:15:35)
      at detectFiberTags (node_modules/enzyme-adapter-react-16/src/detectFiberTags.js:76:15)
      at ReactSixteenAdapter.createMountRenderer (node_modules/enzyme-adapter-react-16/src/ReactSixteenAdapter.js:465:19)
      at ReactSixteenAdapter.createRenderer (node_modules/enzyme-adapter-react-16/src/ReactSixteenAdapter.js:820:51)
      at new ReactWrapper (node_modules/enzyme/src/ReactWrapper.js:113:32)
      at mount (node_modules/enzyme/src/mount.js:10:10)
      at Object.<anonymous> (src/tests/components/DeleteEventFab.test.js:27:17)

Solution:

Enzyme adapter and react needs to be on same version. Inorder to make it work for react-17 we need to utilize this import import Adapter from '@wojtekmaj/enzyme-adapter-react-17';