React Jest test fails to run with ts-jest - Unexpected token on imported file

Question

I have a test for a test for a TSX file written in a JSX file which fails to run due to unexpected token:

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".

I have another test written in JSX for a JSX file which does run. I am using React Testing Library but I don't think this is the issue as the test fails on the file imports.

Stack trace:

 export { default as add } from './add.js';
^^^^^^

SyntaxError: Unexpected token export

  1 | import React from 'react';
> 2 | import { debounce } from 'lodash-es';
    | ^
  3 | 
  4 | interface Props {
  5 |   bodyContent?: string

  at ScriptTransformer._transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:537:17)
  at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:579:25)
  at Object.<anonymous> (components/tsx/TestComponentTSX.tsx:2:1)`

Jest config:

module.exports = {
  moduleDirectories: [
    'node_modules'
  ],
  transform: {
    "\\.tsx?$": "ts-jest",
    "\\.jsx?$": "babel-jest",
  },
  globals: {
    "ts-jest": {
      "tsConfig": '<rootDir>/tsconfig.json'
    }
  }
}

TS Config:

{
  "compilerOptions": {
    "outDir": "./dist/",
    "noImplicitAny": true,
    "module": "es6",
    "target": "es5",
    "jsx": "react",
    "allowJs": true,
    "allowSyntheticDefaultImports": true
  }
}

TestComponentTSX.tsx

import React from 'react';
import { debounce } from 'lodash-es';

interface Props {
  bodyContent?: string
}

function TestComponentTSX(props: Props) {

  const clickHandler = (): void => {
    console.log('I am being clicked!');
  };

  const debouncedClickHandler = debounce(clickHandler, 400)

  return (
    <div>
      <h1>Hello World!</h1>
      <p>{props.bodyContent || 'World...'}</p>
      <button type="button" onClick={debouncedClickHandler}>Click me!</button>
    </div>
  )
}

export default TestComponentTSX;

TestComponentTSX.test.tsx

import React from 'react';
import { render } from '@testing-library/react';
import TestComponentTSX from './TestComponentTSX';

describe('The TSX component is testable', () => {
  test('The component renders', () => {
    // Arrange
    const { getByText } = render(
      <TestComponentTSX />
    );

    // Act
    // Do something

    // Assert
    expect(getByText('Hello World!'));
  })
});

package.json

{
  "name": "jesttypescriptreact",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build-dev": "cross-env NODE_ENV=development webpack"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "lodash-es": "^4.17.15",
    "react": "^16.10.1",
    "react-dom": "^16.10.1"
  },
  "devDependencies": {
    "@babel/core": "^7.6.2",
    "@babel/plugin-proposal-class-properties": "^7.5.5",
    "@babel/plugin-proposal-object-rest-spread": "^7.6.2",
    "@babel/preset-env": "^7.6.2",
    "@babel/preset-react": "^7.0.0",
    "@babel/preset-typescript": "^7.6.0",
    "@testing-library/react": "^9.2.0",
    "@types/jest": "^24.0.18",
    "@types/lodash-es": "^4.17.3",
    "@types/react-dom": "^16.9.1",
    "babel-loader": "^8.0.6",
    "cross-env": "^6.0.0",
    "jest": "^24.9.0",
    "ts-jest": "^24.1.0",
    "ts-loader": "^6.2.0",
    "typescript": "^3.6.3",
    "webpack": "^4.41.0",
    "webpack-cli": "^3.3.9"
  }
}

Answer 1

After messing around with this for absolutely ages it looks like the problem was to do with the lodash-es package and Jest not supporting ES modules. This is mentioned here: https://github.com/facebook/jest/issues/4842

Using @CarlosCrespo answer as a basis I also had to tell babel not to ignore lodash-es when transpiling using the transformIgnorePatterns property to give me the following:

jest.config.js

module.exports = {
  moduleDirectories: [
    'node_modules'
  ],
  transform: {
    "\\.tsx?$": "ts-jest",
    "\\.jsx?$": "babel-jest", // if you have jsx tests too
  },
  globals: {
    "ts-jest": {
      "tsConfig": '<rootDir>/tsconfig.json'
    }
  },
  transformIgnorePatterns: [
    "[/\\\\]node_modules[/\\\\](?!lodash-es/).+\\.js$"
  ],
}

In addition to this I also needed to update my tsconfig.json after another error - Cannot read property createElement of undefined was caused whilst using TypeScript: https://github.com/testing-library/react-testing-library/issues/374

tsconfig.json

{
  "compilerOptions": {
    "outDir": "./dist/",
    "noImplicitAny": true,
    "lib": ["dom", "esnext"],
    "module": "esnext",
    "target": "es5",
    "jsx": "react",
    "esModuleInterop": true,
    "allowJs": true,
    "allowSyntheticDefaultImports": true
  },
  "exclude": ["node_modules"]
}