Question 207399 in React native Question posted in
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React native – Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax

I’m using ignite to create an expo react native app. I’m using this guide https://ignitecookbook.com/docs/recipes/GeneratorComponentTests to create component test files

Here is the first test file


import React from "react"
import { fireEvent, render, screen } from "@testing-library/react-native"
import { HelloWorld } from "../HelloWorld"

describe("HelloWorld", () => {
  it("renders", () => {
    render(<HelloWorld />)
    expect(screen.getByText("Hello")).toBeTruthy()
  })
})

I followed https://reactnativetesting.io/component/setup/ in order to install @testing-library/react-native but now I’m getting

 ● 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:

    /Users/montylennie/AbutFrontend/app/components/specs/HelloWorld.spec.tsx:12
            (0, react_native_1.render)(<HelloWorld_1.HelloWorld />);
                                       ^

    SyntaxError: Unexpected token '<'

      at Runtime.createScriptFromCode (node_modules/jest-runtime/build/index.js:1518:14)
      at asyncGeneratorStep (node_modules/@babel/runtime/helpers/asyncToGenerator.js:3:24)
      at asyncGeneratorStep (node_modules/@babel/runtime/helpers/asyncToGenerator.js:22:9)

Here is my jest.config.js file

const { defaults: tsjPreset } = require("ts-jest/presets")

/** @type {import('@jest/types').Config.ProjectConfig} */
module.exports = {
  ...tsjPreset,
  preset: "jest-expo",
  transformIgnorePatterns: [
    "<rootDir>/node_modules/(react-clone-referenced-element|@react-native-community|react-navigation|@react-navigation/.*|@unimodules/.*|native-base|react-native-code-push)",
    "jest-runner",
  ],
  testPathIgnorePatterns: ["<rootDir>/node_modules/", "<rootDir>/.maestro/", "@react-native"],
  testEnvironment: "jsdom",
  setupFiles: ["<rootDir>/test/setup.ts"],
  setupFilesAfterEnv: ["<rootDir>/jest-setup-after-env.js"],
}

And here is my contents of jest.config.js

import '@testing-library/jest-native/extend-expect';

What am I missing?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I removed ...tsjPreset, and it worked thanks to Victor L's answer


  2. 0

    You have a few problems with your jest.config.js file:

    • You are mixing two presets: jest-expo for Expo apps and ts-jest for TypeScript apps. This can cause conflicts or unexpected behavior,
      because they might have different settings or transformations. You
      should only use one preset at a time, or use the projects option to
      separate different sub-projects.
    • You are using the transformIgnorePatterns option to tell Babel to
      ignore some modules. But this option only works for the default
      transformer, which is babel-jest. If you are using a different
      transformer, like ts-jest, you need to use the transformerConfig
      option to pass the ignore patterns to it.
    • You are using the testEnvironment option to set jsdom, which is a
      browser-like environment for testing web apps. But you are testing a
      React Native app, which is a mobile app that runs on native
      platforms. You should use the node environment instead, which is the
      default for Jest. Or you can use the react-native environment, which
      is provided by the jest-expo preset.

    To fix these issues, you need to update your jest.config.js file and choose the right options for your project. For example, if you are testing an Expo app with TypeScript, you could use something like this:

    module.exports = {
  preset: "jest-expo",
  transform: {
    "^.+\.(js|jsx|ts|tsx)$": "ts-jest",
  },
  globals: {
    "ts-jest": {
      transformerConfig: {
        transformIgnorePatterns: [
          "<rootDir>/node_modules/(react-clone-referenced-element|@react-native-community|react-navigation|@react-navigation/.*|@unimodules/.*|native-base|react-native-code-push)",
          "jest-runner",
        ],
      },
    },
  },
  testPathIgnorePatterns: [
    "<rootDir>/node_modules/",
    "<rootDir>/.maestro/",
    "@react-native",
  ],
  testEnvironment: "react-native",
  setupFiles: ["<rootDir>/test/setup.ts"],
  setupFilesAfterEnv: ["<rootDir>/jest-setup-after-env.js"],
};
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