added unit and integration tests

components/__tests__/BackToTopButton.test.tsx

@@ -0,0 +1,41 @@
+import { render, screen, fireEvent } from '@testing-library/react'
+import '@testing-library/jest-dom'
+import { beforeAll, beforeEach, describe, expect, jest, test } from '@jest/globals'
+import BackToTopButton from '../buttons/BackToTopButton'
+import '@testing-library/jest-dom'
+
+describe('BackToTopButton Test', () => {
+  beforeAll(() => {
+    window.scrollTo = jest.fn()
+
+    Object.defineProperty(window, 'scrollY', { value: 0, writable: true })
+  })
+
+  test('Not displayed when scrollY < 300', () => {
+    render(<BackToTopButton />)
+    fireEvent.scroll(window)
+    expect(screen.queryByRole('button')).toBeNull()
+  })
+
+  test('Displayed when scrollY > 300', () => {
+    render(<BackToTopButton />)
+    Object.defineProperty(window, 'scrollY', { value: 400, writable: true })
+    fireEvent.scroll(window)
+    expect(screen.getByRole('button'))
+  })
+
+  test('When clicked, it calls scrollTo with the correct parameters', () => {
+    render(<BackToTopButton />)
+    Object.defineProperty(window, 'scrollY', { value: 400, writable: true })
+    fireEvent.scroll(window)
+
+    const button = screen.getByRole('button')
+    fireEvent.click(button)
+
+    expect(window.scrollTo).toHaveBeenCalledWith({
+      top: 0,
+      behavior: 'smooth'
+    })
+  })
+})
+

components/__tests__/Contributors.test.tsx

@@ -0,0 +1,37 @@
+import { render, screen, fireEvent } from '@testing-library/react'
+import '@testing-library/jest-dom'
+import { describe, expect, test } from '@jest/globals'
+import { Contributors } from '../index/Contributors'
+
+describe('Contributors', () => {
+  const mockContributors = [
+    { id: '1', url: 'https://github.com/alice', avatar: '/alice.png', name: 'Alice' },
+    { id: '2', url: 'https://github.com/bob', avatar: '/bob.png', name: 'Bob' }
+  ]
+
+  test('renders all contributor images', () => {
+    render(<Contributors contributors={mockContributors} />)
+
+    const aliceImage = screen.getByAltText('Alice')
+    const bobImage = screen.getByAltText('Bob')
+
+    expect(aliceImage).not.toBeNull()
+    expect(bobImage).not.toBeNull()
+
+    const aliceLink = screen.getByRole('link', { name: /alice/i })
+    const bobLink = screen.getByRole('link', { name: /bob/i })
+
+    expect(aliceLink.getAttribute('href')).toBe('https://github.com/alice')
+    expect(bobLink.getAttribute('href')).toBe('https://github.com/bob')
+  })
+
+  test('renders fallback when image fails to load', () => {
+    render(<Contributors contributors={mockContributors} />)
+
+    const aliceImage = screen.getByAltText('Alice')
+    fireEvent.error(aliceImage)
+
+    const fallback = screen.getByText('A')
+    expect(fallback).not.toBeNull()
+  })
+})

components/__tests__/Footer.test.tsx

@@ -0,0 +1,35 @@
+import { render, screen, waitFor } from '@testing-library/react'
+import React from 'react'
+import Footer from '../layout/Footer'
+
+jest.mock('../buttons/Coffee', () => () => <div data-testid="coffee-button" />)
+jest.mock('../buttons/Sponsor', () => () => <div data-testid="sponsor-button" />)
+
+describe('Footer', () => {
+  beforeEach(() => {
+    global.fetch = jest.fn(() =>
+      Promise.resolve({
+        json: () => Promise.resolve({ stargazers_count: 123 })
+      } as Response)
+    ) as jest.Mock
+  })
+
+  afterEach(() => {
+    jest.resetAllMocks()
+  })
+
+  test('renders footer links and components', async () => {
+    render(<Footer />)
+
+    expect(screen.getByText('Technology')).toBeInTheDocument()
+    expect(screen.getByText('Information')).toBeInTheDocument()
+    expect(screen.getByText('Helpful Links')).toBeInTheDocument()
+
+    expect(screen.getByTestId('coffee-button')).toBeInTheDocument()
+    expect(screen.getByTestId('sponsor-button')).toBeInTheDocument()
+
+    await waitFor(() => {
+      expect(screen.getByText('123')).toBeInTheDocument()
+    })
+  })
+})

components/__tests__/Header.test.tsx

@@ -0,0 +1,186 @@
+import { render, screen, fireEvent, waitFor, act } from '@testing-library/react'
+import { useUser } from '@clerk/nextjs'
+import { useRouter } from 'next/router'
+import Header from '../layout/Header'
+
+jest.mock('@clerk/nextjs', () => ({
+  useUser: jest.fn(),
+  UserButton: jest.fn(() => <div data-testid="user-button" />),
+}))
+
+jest.mock('next/router', () => ({
+  useRouter: jest.fn(),
+}))
+
+describe('Header component', () => {
+  const pushMock = jest.fn()
+  const onMock = jest.fn()
+  const offMock = jest.fn()
+
+  beforeEach(() => {
+    (useRouter as jest.Mock).mockReturnValue({
+      push: pushMock,
+      events: { on: onMock, off: offMock },
+    })
+
+    global.fetch = jest.fn(() =>
+      Promise.resolve({
+        json: () => Promise.resolve({ stargazers_count: 123 }),
+      }) as any
+    )
+  })
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  const renderHeader = async () => {
+    await act(async () => {
+      render(<Header />)
+    })
+  }
+
+  test('renders logo and main links', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    await renderHeader()
+
+    expect(screen.getAllByAltText('Logo')[0]).toBeInTheDocument()
+    expect(screen.getByText('Languages')).toBeInTheDocument()
+    expect(screen.getByText('Frameworks')).toBeInTheDocument()
+    expect(screen.getByText('Git')).toBeInTheDocument()
+    expect(screen.getByText('Roadmap')).toBeInTheDocument()
+    expect(screen.getAllByText('Sign In')[0]).toBeInTheDocument()
+  })
+
+  test('fetches GitHub stars and displays them', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    await renderHeader()
+
+    await waitFor(() => {
+      expect(screen.getAllByText('123')[0]).toBeInTheDocument()
+    })
+  })
+
+  test('toggles dropdown menus', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    await renderHeader()
+
+    const languagesButton = screen.getByText('Languages')
+    fireEvent.click(languagesButton)
+    expect(screen.getByText('JavaScript')).toBeInTheDocument()
+
+    fireEvent.click(languagesButton)
+    expect(screen.queryByText('JavaScript')).not.toBeInTheDocument()
+  })
+
+  test('navigates when dropdown item clicked', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    await renderHeader()
+
+    fireEvent.click(screen.getByText('Languages'))
+    fireEvent.click(screen.getByText('JavaScript'))
+    expect(pushMock).toHaveBeenCalledWith('/languages/javascript')
+  })
+
+  test('mobile menu toggles', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+    await renderHeader()
+
+    const menuButton = screen.getByTestId('mobile-menu-button')
+
+    fireEvent.click(menuButton)
+    await waitFor(() => {
+      const lang = screen.getAllByText('Languages')
+      expect(lang.length).toBeGreaterThan(0)
+    })
+
+    fireEvent.click(menuButton)
+    await waitFor(() => {
+      const lang = screen.queryAllByText('Languages')
+      expect(lang.length).toBeGreaterThan(0)
+    })
+  })
+
+  test('renders UserButton if user is logged in', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: { id: '1' }, isLoaded: true })
+
+    await renderHeader()
+
+    expect(screen.getByTestId('user-button')).toBeInTheDocument()
+  })
+
+  test('handles fetch error gracefully', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+    ;(global.fetch as jest.Mock).mockRejectedValueOnce(new Error('Network error'))
+    const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {})
+
+    await renderHeader()
+
+    await waitFor(() => {
+      expect(errorSpy).toHaveBeenCalled()
+    })
+    errorSpy.mockRestore()
+  })
+
+  test('registers and cleans up router.events listeners', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    const { unmount } = render(<Header />)
+
+    await waitFor(() => {
+      expect(onMock).toHaveBeenCalledWith('routeChangeStart', expect.any(Function))
+    })
+
+    unmount()
+    expect(offMock).toHaveBeenCalledWith('routeChangeStart', expect.any(Function))
+  })
+
+  test('toggleSideNav opens and closes side navigation', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+    await renderHeader()
+
+    const menuButton = screen.getByTestId('mobile-menu-button')
+    fireEvent.click(menuButton)
+    fireEvent.click(menuButton)
+    expect(menuButton).toBeInTheDocument()
+  })
+
+  test('dispatches custom event when dropdowns open', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+    const eventSpy = jest.fn()
+    window.addEventListener('dropdownOpened', eventSpy)
+
+    await renderHeader()
+
+    const langBtn = screen.getAllByText('Languages')[0]
+    const fwBtn = screen.getAllByText('Frameworks')[0]
+    const gitBtn = screen.getAllByText('Git')[0]
+    const roadmapBtn = screen.getAllByText('Roadmap')[0]
+
+    fireEvent.click(langBtn)
+    fireEvent.click(fwBtn)
+    fireEvent.click(gitBtn)
+    fireEvent.click(roadmapBtn)
+
+    expect(eventSpy).toHaveBeenCalledTimes(4)
+
+    window.removeEventListener('dropdownOpened', eventSpy)
+  })
+
+  test('navigates for framework', async () => {
+    ;(useUser as jest.Mock).mockReturnValue({ user: null, isLoaded: true })
+
+    await renderHeader()
+
+    const fwBtn = screen.getAllByText('Frameworks')[0]
+    fireEvent.click(fwBtn)
+    fireEvent.click(await screen.findByText('React'))
+    expect(pushMock).toHaveBeenCalledWith('/frameworks/react')
+
+
+  })
+})

components/__tests__/LazyImage.test.tsx

@@ -0,0 +1,39 @@
+import { render, screen } from '@testing-library/react'
+import '@testing-library/jest-dom'
+import { useInView } from 'react-intersection-observer'
+import { describe, expect, test } from '@jest/globals'
+import React from 'react'
+import LazyImage from '../index/LazyImage'
+
+jest.mock('react-intersection-observer', () => ({
+  useInView: jest.fn()
+}))
+
+const mockedUseInView = useInView as unknown as jest.Mock
+
+describe('LazyImage', () => {
+  const mockProps = {
+    src: '/test.png',
+    alt: 'Test Image',
+    width: 100,
+    height: 100
+  }
+
+  test('does not render image when not in view', () => {
+    mockedUseInView.mockReturnValue({ ref: jest.fn(), inView: false })
+
+    render(<LazyImage {...mockProps} />)
+
+    expect(screen.queryByAltText('Test Image')).toBeNull()
+  })
+
+  test('renders image when in view', () => {
+    mockedUseInView.mockReturnValue({ ref: jest.fn(), inView: true })
+
+    render(<LazyImage {...mockProps} />)
+
+    const img = screen.getByAltText('Test Image')
+    expect(img).not.toBeNull()
+    expect(img?.getAttribute('src')).toContain('test.png')
+  })
+})

components/__tests__/LoadingPage.test.tsx

@@ -0,0 +1,48 @@
+import { render, screen } from '@testing-library/react'
+import LoadingPage from '../layout/LoadingPage'
+import { useRouter } from 'next/router'
+import { act } from 'react-dom/test-utils'
+
+jest.mock('next/router', () => ({
+  useRouter: jest.fn(),
+}))
+
+describe('LoadingPage', () => {
+  let pushMock: jest.Mock
+
+  beforeEach(() => {
+    jest.useFakeTimers()
+    pushMock = jest.fn()
+    ;(useRouter as jest.Mock).mockReturnValue({
+      push: pushMock,
+    })
+  })
+
+  afterEach(() => {
+    jest.clearAllMocks()
+    jest.useRealTimers()
+  })
+
+  test('renders logo, title, bouncing dots and redirect text', () => {
+    render(<LoadingPage />)
+
+    expect(screen.getByAltText('FCM Logo')).toBeInTheDocument()
+
+    expect(screen.getByText('Welcome to Fork, Commit, Merge')).toBeInTheDocument()
+
+    expect(screen.getByText('Redirecting you to the homepage...')).toBeInTheDocument()
+
+    const dots = document.querySelectorAll('.animate-bounce')
+    expect(dots.length).toBe(3)
+  })
+
+  test('redirects to home after 3 seconds', () => {
+    render(<LoadingPage />)
+
+    act(() => {
+      jest.advanceTimersByTime(3000)
+    })
+
+    expect(pushMock).toHaveBeenCalledWith('/')
+  })
+})