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MUI5 not working with jest – SyntaxError: Cannot use import statement outside a module

Reproducible repo: https://github.com/hutber/cannotusestatement

What is more worrying is: https://codesandbox.io/s/vigilant-bartik-bmz8x in the sandbox the tests pass. However if you checkout the above repo, which was imported into this sandbox it will not pass locally.

I have no doubt that the issue is my jest does not compile the node_modules that would be needed for running my tests. But I am at a loss now on how to get it working.

I would simply like to be able to run the tests. They do not run currently

test

import React from 'react'
import { renderWithThemeProvider, screen } from 'test-utils'
import { Select } from './Select'

it('renders correctly', () => {
  const tree = renderWithThemeProvider(<Select id="testSelect"></Select>)
  expect(tree).toMatchSnapshot()
})

jest.config.js

module.exports = {
  roots: ['<rootDir>', './src'],
  moduleDirectories: ['<rootDir>', 'node_modules/', './src'],
  transform: {
    '^.+\.(ts|tsx)$': 'ts-jest',
  },
  testEnvironment: 'jsdom',
  testMatch: ['**/*.test.(ts|tsx)', '**/__tests__/*.(ts|tsx)'],
  moduleNameMapper: {
    // Mocks out all these file formats when tests are run
    '\.(jpg|ico|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$': 'identity-obj-proxy',
    '\.(css|less|scss|sass)$': 'identity-obj-proxy',
    'app-config': '<rootDir>/app-config/default',
    '^@components(.*)$': '<rootDir>/src/components$1',
    '^@themes(.*)$': '<rootDir>/src/themes$1',
  },
  coverageThreshold: {
    global: {
      statements: 50,
    },
  },
}

babel.config.js

module.exports = {
  presets: ['@babel/preset-env', '@babel/preset-react'],
  env: {
    test: {
      presets: ['@babel/preset-env', '@babel/preset-react'],
      plugins: [
        [
        'babel-plugin-transform-imports',
        '@babel/plugin-proposal-class-properties',
        'transform-es2015-modules-commonjs',
        'babel-plugin-dynamic-import-node',
        'babel-plugin-styled-components',
      ],
    },
  },
}

package.json

"test": "jest --watchAll=false",

yarn test

(base) [email protected]:/var/www/target/component-library$ yarn test src/components/Select/Select.test.tsx
yarn run v1.22.17
$ jest --watchAll=false src/components/Select/Select.test.tsx
 FAIL  src/components/Select/Select.test.tsx
  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
     • 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/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /var/www/target/component-library/node_modules/@mui/material/styles/styled.js:1
    ({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){import { createStyled, shouldForwardProp } from '@mui/system';
                                                                                      ^^^^^^

    SyntaxError: Cannot use import statement outside a module

      1 | import React from 'react'
    > 2 | import styled from '@mui/material/styles/styled'
        | ^
      3 |
      4 | import MuiSelect, { SelectProps as MuiSelectProps } from '@mui/material/Select'
      5 | import InputLabel from '@mui/material/InputLabel'

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1728:14)
      at Object.<anonymous> (src/components/Select/Select.tsx:2:1)

Test Suites: 1 failed, 1 total
Tests:       0 total
Snapshots:   0 total
Time:        3.272 s

import React from 'react'
import styled from '@mui/material/styles/styled'

import MuiSelect, { SelectProps as MuiSelectProps } from '@mui/material/Select'
import InputLabel from '@mui/material/InputLabel'
import MenuItem from '@mui/material/MenuItem'
import MuiFormControl from '@mui/material/FormControl'

interface ISelect extends MuiSelectProps {
  id: string
  label?: string
  options?: { text: string; option: string }[]
}
const FormControl = styled(MuiFormControl)`
  color: #fff;
  border-radius: 30px;
  width: 180px;
`

export const Select: React.FC<ISelect> = ({ label, id, children, options, ...props }) => {
  return (
    // @ts-ignore
    <FormControl fullWidth hiddenLabel>
      {label && (
        <InputLabel id={`input_${id}`} shrink={false}>
          {label}
        </InputLabel>
      )}
      <MuiSelect id={id} {...props}>
        {options && options.map(({ text, option }: { text: string; option: string }) => <MenuItem value={option}>{text}</MenuItem>)}
        {children && children}
      </MuiSelect>
    </FormControl>
  )
}

export default Select

Answer

First you have two exports in your Select.tsx file. Just use the default export, so change line 20 to:

const Select: React.FC<ISelect> = ({ label, id, children, options, ...props }) => {

Then in your Select.test.tsx file change to:

import Select from './Select'

Finally to fix the import issue change your code in Select.tsx to:

import { styled } from '@mui/material'

This is a fairly common issue as can be seen here.