feat: add unit tests for requireRole middleware

This commit adds unit tests for the requireRole middleware to ensure proper role-based access control implementation. The tests cover successful access, insufficient permissions, and unauthorized access scenarios.

backend/tests/requireRole.test.js

@@ -0,0 +1,56 @@
+const { requireRole, hasRole } = require('../src/middleware/requireRole');
+
+describe('requireRole middleware', () => {
+  it('should allow access for users with correct role', () => {
+    const req = { user: { role: 'admin' } };
+    const res = {
+      status: jest.fn().mockReturnThis(),
+      json: jest.fn()
+    };
+    const next = jest.fn();
+
+    const middleware = requireRole(['admin']);
+    middleware(req, res, next);
+
+    expect(next).toHaveBeenCalled();
+    expect(res.status).not.toHaveBeenCalled();
+  });
+
+  it('should deny access for users with incorrect role', () => {
+    const req = { user: { role: 'user' } };
+    const res = {
+      status: jest.fn().mockReturnThis(),
+      json: jest.fn()
+    };
+    const next = jest.fn();
+
+    const middleware = requireRole(['admin']);
+    middleware(req, res, next);
+
+    expect(next).not.toHaveBeenCalled();
+    expect(res.status).toHaveBeenCalledWith(403);
+    expect(res.json).toHaveBeenCalledWith({ error: 'Insufficient permissions' });
+  });
+
+  it('should deny access for unauthenticated users', () => {
+    const req = { user: null };
+    const res = {
+      status: jest.fn().mockReturnThis(),
+      json: jest.fn()
+    };
+    const next = jest.fn();
+
+    const middleware = requireRole(['admin']);
+    middleware(req, res, next);
+
+    expect(next).not.toHaveBeenCalled();
+    expect(res.status).toHaveBeenCalledWith(401);
+    expect(res.json).toHaveBeenCalledWith({ error: 'Authorization required' });
+  });
+
+  it('should correctly check role with hasRole helper', () => {
+    expect(hasRole('admin', ['admin'])).toBe(true);
+    expect(hasRole('user', ['admin'])).toBe(false);
+    expect(hasRole('moderator', ['admin', 'moderator'])).toBe(true);
+  });
+});