Testing in Decomposed UIs

1. Introduction

In the world of Micro Frontends, applications are often split into smaller, more manageable pieces called decomposed UIs. Testing these components is crucial to ensure they function correctly both in isolation and as part of the larger application.

2. Key Concepts

2.1 Micro Frontends

Micro Frontends are an architectural style where a single application is divided into multiple smaller applications or components, each owned by different teams.

2.2 Decomposed UIs

Decomposed UIs refer to the individual micro frontend components that can be developed, tested, and deployed independently.

2.3 Testing Types

Unit Testing
Integration Testing
End-to-End Testing

3. Testing Strategies

Implementing effective testing strategies is essential for maintaining the integrity of decomposed UIs.

3.1 Unit Testing

Unit tests focus on individual components in isolation.

Tip: Use frameworks like Jest or Mocha for unit tests.

Example Unit Test


import { render, screen } from '@testing-library/react';
import MyComponent from './MyComponent';

test('renders learn react link', () => {
  render();
  const linkElement = screen.getByText(/learn react/i);
  expect(linkElement).toBeInTheDocument();
});

3.2 Integration Testing

Integration tests verify that multiple components work together as expected.

Example Integration Test


import { render, screen } from '@testing-library/react';
import App from './App';

test('renders the main app component', () => {
  render();
  const titleElement = screen.getByText(/Welcome to My App/i);
  expect(titleElement).toBeInTheDocument();
});

3.3 End-to-End Testing

End-to-End tests assess the entire application workflow, simulating user scenarios.

Example E2E Test


describe('My App E2E', () => {
  it('should navigate to the correct page', () => {
    cy.visit('http://localhost:3000');
    cy.get('a').contains('Learn More').click();
    cy.url().should('include', '/learn-more');
  });
});

4. Best Practices

Isolate tests for individual components.
Mock external services to avoid dependencies during testing.
Use continuous integration for automated test execution.
Document test cases for clarity.

5. FAQ

What is the importance of testing in Micro Frontends?

Testing ensures that each micro frontend operates correctly and integrates seamlessly with others, preventing regressions and bugs.

How can I manage dependencies in tests?

Use mocking libraries to simulate dependencies without relying on actual services during testing.

What tools are recommended for testing Micro Frontends?

Jest, Mocha, Cypress, and Testing Library are popular choices for testing Micro Frontends.