#1841 Add tests for <LoadingSpinner> component

frontend/__tests__/unit/components/LoadingSpinner.test.tsx

@@ -0,0 +1,72 @@
+import { render, screen } from '@testing-library/react'
+import LoadingSpinner from 'components/LoadingSpinner'
+
+jest.mock('next/image', () => ({
+  __esModule: true,
+  // eslint-disable-next-line @next/next/no-img-element, jsx-a11y/alt-text
+  default: (props) => <img {...props} />,
+}))
+
+describe('<LoadingSpinner />', () => {
+  it('renders without crashing', () => {
+    render(<LoadingSpinner />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images.length).toBe(2) // One for light, one for dark
+  })
+
+  it('handles invalid imageUrl input gracefully', () => {
+    // With the original component, we test that it works with undefined/null
+    render(<LoadingSpinner imageUrl={undefined} />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images.length).toBe(2)
+    // Should fallback to default images when no valid input is provided
+    expect(images[0].getAttribute('src')).toContain('white')
+    expect(images[1].getAttribute('src')).toContain('black')
+  })
+  it('has appropriate alt text for accessibility', () => {
+    render(<LoadingSpinner />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images.length).toBe(2)
+  })
+  it('applies correct Tailwind classes for dark/light mode', () => {
+    render(<LoadingSpinner imageUrl="/test.png" />)
+    const images = screen.getAllByAltText('Loading indicator')
+
+    // First image should be for dark mode (hidden in light, visible in dark)
+    expect(images[0]).toHaveClass('hidden', 'rounded-full', 'dark:block')
+
+    // Second image should be for light mode (visible in light, hidden in dark)
+    expect(images[1]).toHaveClass('rounded-full', 'dark:hidden')
+  })
+
+  it('renders default image if no imageUrl is provided', () => {
+    render(<LoadingSpinner />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images[0].getAttribute('src')).toContain('white') // dark image
+    expect(images[1].getAttribute('src')).toContain('black') // light image
+  })
+
+  it('renders custom image when imageUrl is provided', () => {
+    const customUrl = '/img/spinner_white.png'
+    render(<LoadingSpinner imageUrl={customUrl} />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images[0].getAttribute('src')).toBe(customUrl) // Should use the exact custom URL
+    expect(images[1].getAttribute('src')).toBe('/img/spinner_black.png') // Should transform white to black
+  })
+
+  it('renders spinner container with correct styles', () => {
+    render(<LoadingSpinner />)
+    const fadeContainer = document.querySelector('.animate-fade-in-out')
+    expect(fadeContainer).toBeInTheDocument()
+    expect(fadeContainer?.className).toContain('animate-fade-in-out')
+  })
+
+  it('has appropriate alt text and accessibility image role', () => {
+    render(<LoadingSpinner />)
+    const images = screen.getAllByAltText('Loading indicator')
+    expect(images[0]).toBeInTheDocument()
+    expect(images[0].tagName.toLowerCase()).toBe('img')
+    expect(images[1]).toBeInTheDocument()
+    expect(images[1].tagName.toLowerCase()).toBe('img')
+  })
+})