feat: Add unit tests for authentication and user profile management

habitTrackerApp/jest.setup.js

@@ -1 +1,5 @@
 import '@testing-library/jest-dom'
+
+// Mock environment variables for tests
+process.env.NEXT_PUBLIC_SUPABASE_URL = 'https://test-url.supabase.co'
+process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY = 'test-anon-key'

habitTrackerApp/package.json

@@ -51,6 +51,7 @@
     "eslint-config-next": "^15.5.5",
     "jest": "^30.2.0",
     "jest-environment-jsdom": "^30.2.0",
+    "node-mocks-http": "^1.17.2",
     "postcss": "^8.5.6",
     "tailwindcss": "^3.4.15",
     "ts-jest": "^29.4.5",

habitTrackerApp/tests/unit/GoogleCalendarConnect.test.tsx

@@ -0,0 +1,95 @@
+// Mock Supabase to avoid ESM transform errors
+jest.mock('@supabase/auth-helpers-nextjs', () => ({
+  createClientComponentClient: () => ({
+    from: jest.fn(() => ({
+      select: jest.fn(() => ({
+        eq: jest.fn(() => ({
+          single: jest.fn()
+        }))
+      }))
+    }))
+  })
+}));
+
+import { render, screen, waitFor } from '@testing-library/react';
+import GoogleCalendarConnect from '../../src/app/components/GoogleCalendarConnect';
+
+// Mock user object
+const mockUser = {
+  id: 'test-user-id',
+  email: 'test@example.com',
+  user_metadata: {}
+};
+
+describe('GoogleCalendarConnect Component', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should render the component', async () => {
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    // Wait for loading to complete and check for the main heading
+    await waitFor(() => {
+      expect(screen.getByText('Google Calendar')).toBeInTheDocument();
+    });
+  });
+
+  it('should show loading state initially', () => {
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    // Check for loading spinner
+    const spinner = document.querySelector('.animate-spin');
+    expect(spinner).toBeInTheDocument();
+  });
+
+  it('should handle connection check', async () => {
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    // Wait for the component to load and show the "not connected" state
+    await waitFor(() => {
+      expect(screen.getByText('Connect Google Calendar')).toBeInTheDocument();
+    });
+  });
+
+  it('should handle no connection found', async () => {
+    const mockSupabase = require('@supabase/auth-helpers-nextjs').createClientComponentClient();
+
+    // Mock no connection found
+    mockSupabase.from().select().eq().single.mockRejectedValue(new Error('No connection'));
+
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    await waitFor(() => {
+      expect(screen.getByText('Connect Google Calendar')).toBeInTheDocument();
+    });
+  });
+
+  it('should handle expired token', async () => {
+    const mockSupabase = require('@supabase/auth-helpers-nextjs').createClientComponentClient();
+
+    // Mock expired token
+    mockSupabase.from().select().eq().single.mockResolvedValue({
+      data: {
+        id: 'token-id',
+        expires_at: new Date(Date.now() - 3600000).toISOString() // 1 hour ago
+      },
+      error: null
+    });
+
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    await waitFor(() => {
+      expect(screen.getByText('Connect Google Calendar')).toBeInTheDocument();
+    });
+  });
+
+  it('should display user information', async () => {
+    render(<GoogleCalendarConnect user={mockUser as any} />);
+
+    // Wait for loading to complete and check for the main heading
+    await waitFor(() => {
+      expect(screen.getByText('Google Calendar')).toBeInTheDocument();
+    });
+  });
+});