React Native with Typescript and Jest is broken after 0.57 Update: Couldn't find preset “module:metro-react-native-babel-preset” relative to directory

Question

If you integrate test with Jest and Enzyme in the new React Version 0.57 and TypeScript, they won't work. Here are the steps to reproduce:

Create a new React Native project:

react-native init MyApp -package "com.my.app" --template typescript && node MyApp/setup.js

Install all Jest and Enzyne related packages:

npm install --save-dev react-dom enzyme enzyme-react-adapter-16 jest-fetch-mock ts-jest

Add the jest configuration:

"jest": {
  "preset": "react-native",
  "moduleFileExtensions": [
    "ts",
    "tsx",
    "js"
  ],
  "transform": {
    "^.+\\.(js)$": "<rootDir>/node_modules/babel-jest",
    "\\.(ts|tsx)$": "<rootDir>/node_modules/ts-jest/preprocessor.js"
  },
  "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
  "testPathIgnorePatterns": [
    "\\.snap$",
    "<rootDir>/node_modules/"
  ],
  "cacheDirectory": ".jest/cache",
  "setupFiles": [
    "./tests/setup.js"
  ]
}

Add a file tests/setup.js and include the following configuration:

import Enzyme from "enzyme";
import Adapter from "enzyme-adapter-react-16";
import { NativeModules } from "react-native";

global.fetch = require("jest-fetch-mock"); // eslint-disable-line no-undef
jest.mock("react-native-config");
Enzyme.configure({ adapter: new Adapter() });

Last but not least add a basic test (App.test.tsx) to check if Jest and Enzyme work:

import React from "react";
import { shallow } from "enzyme";
import { View } from "react-native";
import App from "./App";

const createTestProps = props => ({
  ...props
});

describe("App", () => {
  describe("rendering", () => {
    let wrapper;
    let props;
    beforeEach(() => {
      props = createTestProps({});
      wrapper = shallow(<App {...props} />);
    });

    it("should render a <View />", () => {
      expect(wrapper.find(View)).toHaveLength(1);
    });
  });
});

If you now try to run the test, the error message you get is:

 FAIL  app/App.test.tsx
  ● Test suite failed to run

    Couldn't find preset "module:metro-react-native-babel-preset" relative to directory "<Directory"

Edit

It seems like this has something to do with Babel.

Answer 1

I found the answer here in this issue: https://github.com/facebook/metro/issues/242#issuecomment-421139247

Basically, add this to your Jest section in package.json:

"transform": { "^.+\\.js$": "<rootDir>/node_modules/react-native/jest/preprocessor.js" }

Answer 2

had a similar issue when upgrading to 0.57, my package.json still contained an entry for babel-preset-react-native (which is now deprecated in favor of metro-react-native-babel-preset). All I had to do was

yarn remove babel-preset-react-native

and then

yarn add metro-react-native-babel-preset --dev

Lastly, make sure you change your .babelrc from

{
  "presets": ["react-native"]
}

to

{
  "presets": ["module:metro-react-native-babel-preset"]
}

More info can be found here

Answer 3

If I use "presets": ["react-native"] then production/development is broken but tests are working.

If I use "presets": ["module:metro-react-native-babel-preset"] then tests are broken but production/development is working.

Not sure why it's like that but a .babelrc solution for me like below works both for development/production and tests. Just add env parameter to your .babelrc file.

"env": {
    "test": {
        "presets": ["react-native"]
    },
    "production": {
        "presets": ["module:metro-react-native-babel-preset"]
    },
    "development": {
        "presets": ["module:metro-react-native-babel-preset"]
    }
}