adopt-a-street/frontend/src/setupTests.js

// jest-dom adds custom jest matchers for asserting on DOM nodes.
// allows you to do things like:
// expect(element).toHaveTextContent(/react/i)
// learn more: https://github.com/testing-library/jest-dom
import '@testing-library/jest-dom';

// MSW (Mock Service Worker) for API mocking
import { server } from './mocks/server';

// Establish API mocking before all tests
beforeAll(() => server.listen({ onUnhandledRequest: 'warn' }));

// Reset any request handlers that we may add during the tests,
// so they don't affect other tests
afterEach(() => server.resetHandlers());

// Clean up after the tests are finished
afterAll(() => server.close());

// Mock localStorage
const localStorageMock = {
  getItem: jest.fn(),
  setItem: jest.fn(),
  removeItem: jest.fn(),
  clear: jest.fn(),
};
global.localStorage = localStorageMock;

// Mock window.matchMedia (used by some components)
Object.defineProperty(window, 'matchMedia', {
  writable: true,
  value: jest.fn().mockImplementation(query => ({
    matches: false,
    media: query,
    onchange: null,
    addListener: jest.fn(), // Deprecated
    removeListener: jest.fn(), // Deprecated
    addEventListener: jest.fn(),
    removeEventListener: jest.fn(),
    dispatchEvent: jest.fn(),
  })),
});

// Suppress console errors during tests (except actual errors)
const originalError = console.error;
beforeAll(() => {
  console.error = (...args) => {
    if (
      typeof args[0] === 'string' &&
      (args[0].includes('Warning: ReactDOM.render') ||
       args[0].includes('Warning: useLayoutEffect') ||
       args[0].includes('Not implemented: HTMLFormElement.prototype.submit'))
    ) {
      return;
    }
    originalError.call(console, ...args);
  };
});

afterAll(() => {
  console.error = originalError;
});