SyntaxError: Missing initializer in const declaration

Question

I am writing a simple test using react-native-testing-library (my first steps with that library) in my react native expo app. But I am getting a confused error coming from somewhere inside react-native code base itself. Either there is something wrong with my code or there is a bug with react-native-testing-library npm library.

Here is simple jest test:

describe("AppTitle", () => {
  it("should display applicaton title", () => {
    const { getByText } = render(<AppTitle />);
    expect(getByText('App Name')).toBeTruthy();
  });
});

And here is the simple <AppTitle /> component (just a View and a Text)

export const AppTitle = () => {
  return (
    <View>
      <Text>App Name</Text>
    </View>
  );
};

But I am getting this error when I run the test:

...../Utilities/warnOnce.js:15

const warnedKeys: {[string]: boolean} = {};
      ^^^^^^^^^^

SyntaxError: Missing initializer in const declaration

at ScriptTransformer.transformAndBuildScript (node_modules/@jest/transform/build/ScriptTransformer.js:471:17)
at ScriptTransformer.transform (node_modules/@jest/transform/build/ScriptTransformer.js:513:25)
at Object.<anonymous> (node_modules/react-native/Libraries/react-native/react-native-implementation.js:14:18)
...

This is a simple and straight forward template. Any help from a react-native + react-native-testing-library would be appreciate.

1. react: 16.8.3
2. react-native: fork from Expo 33
3. jest-expo: "^33.0.2"
4. react-native-testing-library": "1.7.0"

Answer 1

I resolved this added "preset": "react-native" in jest.config.js file

Answer 2

I am using expo in my project. I have same issue. i forgot to add "preset": "jest-expo" to package.json. i added then the problem solved.

 "jest": { "preset": "jest-expo" },