Test suite failed to run ReferenceError: TextEncoder is not defined

Question

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I am trying to test my project using a mock API instead of a real one to save money. However, when I add the following code to my setupTests.js file:

// setupTests.js
import { server } from "./mocks/server";

beforeAll(() => server.listen());
afterEach(() => server.resetHandlers());
afterAll(() => server.close());

I get this error:

Test suite failed to run

    ReferenceError: TextEncoder is not defined

      1 | // mocks/server.js
    > 2 | import { setupServer } from 'msw/node';
        | ^
      3 | import { handlers } from './handlers'; // your request handlers
      4 |
      5 | export const server = setupServer(...handlers);

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What We Tried:

1. Polyfill for TextEncoder and TextDecoder:

   • We tried adding a polyfill for TextEncoder and TextDecoder in the setupTests.js file.
   • Code added:

     const { TextEncoder, TextDecoder } = require('util');
     global.TextEncoder = TextEncoder;
     global.TextDecoder = TextDecoder;
     

2. Ensured Jest Environment is jsdom:

   • We checked and ensured that the Jest environment is set to jsdom to simulate a browser-like environment.
   • Jest configuration:

     // jest.config.js
     module.exports = {
       testEnvironment: 'jsdom',
       setupFilesAfterEnv: ['./setupTests.js'],
     };
     

3. Updated Dependencies:

   • We updated all dependencies to their latest versions to ensure compatibility.
   • Command used:

     npm update
     

4. Verified Mock Server Setup:

   • We ensured the mock server setup in mocks/server.js was correct.
   • Example:

     // mocks/server.js
     import { setupServer } from 'msw/node';
     import { handlers } from './handlers';
     
     export const server = setupServer(...handlers);
     

5. Created a Minimal Test Case:

   • We created a minimal test case to isolate the problem.
   • Test code:

     // src/__tests__/example.test.js
     import { render, screen } from '@testing-library/react';
     import '@testing-library/jest-dom/extend-expect';
     import React from 'react';
     
     const TestComponent = () => <div>Hello, World!</div>;
     
     test('renders hello world', () => {
       render(<TestComponent />);
       expect(screen.getByText('Hello, World!')).toBeInTheDocument();
     });
     

What We Expected:

• Polyfill for TextEncoder and TextDecoder:

  • We expected adding the polyfill to make TextEncoder and TextDecoder available in the Node.js environment, resolving the error.

• Jest Environment as jsdom:

  • We expected using the jsdom environment to simulate a browser-like environment where TextEncoder and TextDecoder would be available.

• Updated Dependencies:

  • We expected updating dependencies to resolve any compatibility issues that might be causing the error.

• Verified Mock Server Setup:

  • We expected ensuring the correct setup of the mock server to eliminate any configuration issues.

• Minimal Test Case:

  • We expected the minimal test case to help identify if there were any fundamental issues with the setup.

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