TDD:Typescript Testing testing-library/react-native.

Expo SDK
1

Hi,
Iam unable to implement Jest with Typescript, it doesn’t look like Expo has sufficient documentation in this matter.

I tried to run a basic test in a new Bare typescript project and it fails but if I change to normal .Js file it works please help.

import React from 'react';
import { render } from '@testing-library/react-native';

import App from './App';

test('it renders all inputs as expected', () => {
  const { toJSON } = render(<App />);

  expect(toJSON()).toMatchSnapshot();
});

Error message:
console.error
Warning: React.createElement: type is invalid – expected a string (for built-in c
omponents) or a class/function (for composite components) but got: object.

   5 | 
   6 | test('it renders all inputs as expected', () => {
>  7 |   const { toJSON } = render(<App />);
     |                             ^
   8 | 
   9 |   expect(toJSON()).toMatchSnapshot();
  10 | });

Package.json

"devDependencies": {
    "@babel/core": "^7.8.6",
    "@testing-library/jest-native": "^3.4.2",
    "@testing-library/react-native": "^7.0.2",
    "@types/jest": "^26.0.13",
    "@types/react": "~16.9.41",
    "@types/react-native": "~0.62.13",
    "@types/react-test-renderer": "^16.9.3",
    "jest": "^26.4.2",
    "jest-expo": "^38.0.2",
    "jest-fetch-mock": "^3.0.3",
    "react-test-renderer": "^16.13.1",
    "ts-jest": "^26.3.0",
    "typescript": "~3.9.5"
  },

I look forward to your help.

Thank you

2

Just add the last line in your jest.configs.js file

preset: 'jest-expo',
moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],

Stackoverflow

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