6

I've forked the following react native base project and converted it from JavaScript to TypeScript. The app runs correctly but Jest tests fail with the following error. I expected the test to run successfully and Jest to run any transforms where necessary:

 C:\Users\brian-varley\Documents\Projects\react-native-base\node_modules\redux-flipper\node_modules\react-native-flipper\index.js:11
import {NativeModules, NativeEventEmitter} from 'react-native';
^^^^^^

SyntaxError: Cannot use import statement outside a module

  at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1350:14)
  at Object.<anonymous> (node_modules/redux-flipper/lib/index.js:3:32)

The cause of the error seems to come from this import statement inside the react-native-flipper package:

import {NativeModules, NativeEventEmitter} from 'react-native';

I've tried a solution here from StackOverflow which suggests using babel-jestas the transformer in the jest.config.js file to no avail - https://stackoverflow.com/a/64223627/1829251. I also looked through this thread but didn't find a solution - https://github.com/facebook/jest/issues/9292

Question:

How can you configure Jest to transform modules containing invalid syntax?

Environment

"react-native": "0.63.2",
"jest": "^26.6.3",
"metro-react-native-babel-preset": "0.59.0",
"babel-jest": "^25.1.0",
"ts-jest": "^26.5.3",

Config Code Samples:

jest.config.js:

module.exports =  {
    preset: "react-native",
    transform: {
      "^.+\\.tsx?$": "ts-jest",
      "^.+\\.(js|jsx)$": "babel-jest",
      "node_modules/variables/.+\\.(j|t)sx?$": "babel-jest"
    },
    testRegex: "(/src/.*\\.(test|spec))\\.(jsx?|tsx?|ts|js)$",
    transformIgnorePatterns: [
      "node_modules/(?!(jest-)?react-native|react-(native|universal|navigation)-(.*)|@react-native-community/(.*)|@react-navigation/(.*)|bs-platform|@rootstrap/redux-tools)"
    ],
    setupFiles: [
      "./tests/__mocks__/index.js",
      "<rootDir>/node_modules/react-native-gesture-handler/jestSetup.js"
    ],
    moduleFileExtensions: [
      "ts",
      "tsx",
      "js",
      "jsx",
      "json",
      "node"
    ]
  }

babel.config.js:

module.exports = {
  presets: ['module:metro-react-native-babel-preset'],
  plugins: [
    [
      'module-resolver',
      {
        alias: {
          actions: './src/actions',
          httpClient: './src/httpClient',
          services: './src/services',
          components: './src/components',
          constants: './src/constants',
          screens: './src/screens',
          hooks: './src/hooks',
          locale: './src/locale',
          reducers: './src/reducers',
          selectors: './src/selectors',
          store: './src/store',
          utils: './src/utils',
          navigators: './src/navigators',
          validations: './src/validations',
        },
      },
    ],
  ],
};

tsconfig.json:

{
    "compilerOptions": {
      "target": "es6",
      "module": "commonjs",
      "moduleResolution": "node",
      "jsx": "react",
      "outDir": "./dist",
      "experimentalDecorators": true,
      "emitDecoratorMetadata": true,
      "allowSyntheticDefaultImports": true,
      "strict": true,
      "skipLibCheck": true,
      "declaration": true,
      "noUnusedLocals": true,
      "suppressImplicitAnyIndexErrors": true,
      "baseUrl": "./",
    },
    "exclude": [
      "node_modules",
    ]
  }
Brian Var
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  • You already ignore this module in transformIgnorePatterns . I'm quite sure you shouldn't try to load a real one as this will require you to simulate native in Node, i.e. mock everything it uses from `react-native` to the point it meets the expectations. – Estus Flask Apr 06 '21 at 06:44

1 Answers1

3
module.exports =  {
preset: "react-native",
transform: {
    "^.+\\.ts?$": "ts-jest",
    "^.+\\.tsx?$": "ts-jest",
    "^.+\\.js$": "<rootDir>/node_modules/react-native/jest/preprocessor.js"
  },
testRegex: "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)?$",
  transformIgnorePatterns: [
    "node_modules/(?!(jest-)?react-native|react-(native|universal|navigation)-(.*)|@react-native-community/(.*)|@react-navigation/(.*)|bs-platform|@rootstrap/redux-tools)"
  ],
  setupFiles: [
    "./tests/__mocks__/index.js",
    "<rootDir>/node_modules/react-native-gesture-handler/jestSetup.js"
  ],
  moduleFileExtensions: [
    "ts",
    "tsx",
    "js",
    "jsx",
    "json",
    "node"
  ],
  moduleNameMapper: {
    "^.+\\.(css|less|scss)$": "identity-obj-proxy"
  },
  moduleDirectories: [
    "node_modules",
    "src"
  ],
  }

Can you please try this file and try to create new test.

ashish chaklasiya
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