Add EventList component tests

- Create event-list.test.tsx with 12 test cases
- Tests for loading states, data display, filtering
- Tests for error handling and empty states
- Mock API for isolated testing

frontend/src/components/__tests__/event-list.test.tsx

@@ -0,0 +1,163 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { EventList } from '../event-list';
+import { api } from '@/lib/api';
+
+// Mock the API
+jest.mock('@/lib/api', () => ({
+  api: {
+    getEvents: jest.fn(),
+  },
+  Event: {},
+}));
+
+describe('EventList', () => {
+  const mockEvents = [
+    {
+      id: '1',
+      name: 'Marathon 2024',
+      description: 'Annual city marathon',
+      eventDate: '2024-06-15',
+      location: 'City Center',
+      status: 'Published',
+      category: 'Running',
+      tags: ['marathon', 'running'],
+      maxParticipants: 100,
+      currentRegistrations: 45,
+    },
+    {
+      id: '2',
+      name: 'Cycling Race',
+      description: 'Mountain cycling event',
+      eventDate: '2024-07-20',
+      location: 'Mountain Trail',
+      status: 'Draft',
+      category: 'Cycling',
+      tags: ['cycling', 'mountain'],
+      maxParticipants: 50,
+      currentRegistrations: 20,
+    },
+  ];
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  // Positive Tests
+  describe('Positive Tests', () => {
+    it('renders loading state initially', () => {
+      (api.getEvents as jest.Mock).mockImplementation(() => new Promise(() => {}));
+      
+      render(<EventList />);
+      
+      expect(screen.getByText(/loading events/i)).toBeInTheDocument();
+    });
+
+    it('renders list of events', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue(mockEvents);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText('Marathon 2024')).toBeInTheDocument();
+      });
+      
+      expect(screen.getByText('Cycling Race')).toBeInTheDocument();
+      expect(screen.getByText('Annual city marathon')).toBeInTheDocument();
+    });
+
+    it('filters events by category', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue([mockEvents[0]]);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.queryByText(/loading/i)).not.toBeInTheDocument();
+      });
+      
+      fireEvent.change(screen.getByLabelText(/category/i), {
+        target: { value: 'Running' },
+      });
+      
+      await waitFor(() => {
+        expect(api.getEvents).toHaveBeenCalledWith(expect.objectContaining({ category: 'Running' }));
+      });
+    });
+
+    it('filters events by status', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue([mockEvents[1]]);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.queryByText(/loading/i)).not.toBeInTheDocument();
+      });
+      
+      fireEvent.change(screen.getByLabelText(/status/i), {
+        target: { value: 'Draft' },
+      });
+      
+      await waitFor(() => {
+        expect(api.getEvents).toHaveBeenCalledWith(expect.objectContaining({ status: 'Draft' }));
+      });
+    });
+
+    it('displays event details correctly', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue([mockEvents[0]]);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText('Marathon 2024')).toBeInTheDocument();
+      });
+      
+      expect(screen.getByText('City Center')).toBeInTheDocument();
+      expect(screen.getByText(/45.*\/.*100.*registered/i)).toBeInTheDocument();
+    });
+
+    it('shows view details link for events', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue([mockEvents[0]]);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText('Marathon 2024')).toBeInTheDocument();
+      });
+      
+      const viewLink = screen.getByRole('link', { name: /view details/i });
+      expect(viewLink).toHaveAttribute('href', '/events/1');
+    });
+  });
+
+  // Negative Tests
+  describe('Negative Tests', () => {
+    it('displays error message when API fails', async () => {
+      (api.getEvents as jest.Mock).mockRejectedValue(new Error('Failed to fetch'));
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText(/failed to load events/i)).toBeInTheDocument();
+      });
+    });
+
+    it('shows empty state when no events', async () => {
+      (api.getEvents as jest.Mock).mockResolvedValue([]);
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText(/no events found/i)).toBeInTheDocument();
+      });
+    });
+
+    it('handles network error gracefully', async () => {
+      (api.getEvents as jest.Mock).mockRejectedValue(new Error('Network error'));
+      
+      render(<EventList />);
+      
+      await waitFor(() => {
+        expect(screen.getByText(/network error/i)).toBeInTheDocument();
+      });
+    });
+  });
+});