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

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"]}

Looks like you have to add this to your Jest config file

"transform": {  "\\.tsx?$": "ts-jest",  "\\.jsx?$": "babel-jest", // if you have jsx tests too},"globals": {  "ts-jest": {    "tsConfig": pathToYourTsConfigFile  }}

more on that here: https://jestjs.io/docs/en/configuration.html#transform-object-string-pathtotransformer-pathtotransformer-object and here https://kulshekhar.github.io/ts-jest/user/config/

I've since discovered another alternative for the specific case of lodash-es. You can use the normal lodash library and just import the function you need. You can then get the benefit of the lodash-es package without needing to use transformIgnorePatterns.

E.g:

import camelCase from 'lodash/camelCase';camelCase('my string');