Advanced Micro Frontend Testing setup with Jest and Cypress

Introduce the significance of testing in micro frontend applications, where multiple teams may independently develop and deploy components. Explain how Jest (unit/integration) and Cypress (E2E) can help maintain reliability in this architecture.

1. Setting Up Jest for Micro Frontends

Step 1: Configure Jest in a Micro Frontend Module

// jest.config.js
module.exports = {
  setupFilesAfterEnv: ["<rootDir>/jest.setup.js"],
  moduleNameMapper: {
    "^@module/(.*)$": "<rootDir>/src/$1"
  }
};

Step 2: Writing Unit Tests for Shared Components

// Example.test.js
import React from 'react';
import { render } from '@testing-library/react';
import SharedComponent from '@module/shared/SharedComponent';

test('renders component successfully', () => {
  const { getByText } = render(<SharedComponent />);
  expect(getByText(/Hello World/i)).toBeInTheDocument();
});

2. Integration Tests for Federated Modules with Jest

Step 1: Mock Module Federation with Jest Mocks

jest.mock('moduleA', () => ({
  loadComponent: jest.fn(() => import('@moduleA/Component')),
}));

Step 2: Test Interactions Between Micro Frontends

test('Module B uses data from Module A', async () => {
  // Setup code to test interaction between Module A and B
});

3. Configuring Cypress for End-to-End Testing

Step 1: Set Up Cypress in a Micro Frontend Project

// cypress.config.js
module.exports = {
  e2e: {
    baseUrl: 'http://localhost:3000',
  },
};

Step 2: Writing Cross-Micro Frontend E2E Tests

// e2eTest.spec.js
describe('Micro Frontend E2E Test', () => {
  it('should load Module A and Module B seamlessly', () => {
    cy.visit('/');
    cy.get('[data-testid=moduleA-element]').should('be.visible');
    cy.get('[data-testid=moduleB-element]').should('be.visible');
  });
});

4. Mocking Network Requests Across Micro Frontends

Step 1: Mocking API Calls in Cypress

cy.intercept('GET', '/api/moduleA/data', { fixture: 'moduleA-data.json' });

Step 2: Testing Fallbacks and Error States

it('should show error on network failure', () => {
  cy.intercept('GET', '/api/moduleA/data', { statusCode: 500 });
  cy.visit('/');
  cy.get('[data-testid=error-message]').should('contain', 'Failed to load data');
});

By following these steps, you can effectively setup Micro Frontend Testing framework with Jest and Cypress

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