Add Jest test infrastructure for admin dashboard TDD

- Configure Jest with mongodb-memory-server for isolated testing
- Add phase 1-4 test suites covering all admin requirements
- Add test helpers and setup/teardown utilities
- Install jest, supertest, mongodb-memory-server dependencies

__tests__/helpers/testHelpers.js

@@ -0,0 +1,156 @@
+const { MongoClient, ObjectId } = require('mongodb');
+const jwt = require('jsonwebtoken');
+
+// Counter for generating unique identifiers within the same millisecond
+let uniqueCounter = 0;
+
+/**
+ * Create a test Express app instance with database connection
+ * This creates a minimal Express app for testing admin routes
+ */
+async function createTestApp(db) {
+  const express = require('express');
+  const cookieParser = require('cookie-parser');
+
+  const app = express();
+  app.use(express.json());
+  app.use(cookieParser());
+
+  // Store db in app.locals for middleware access
+  app.locals.db = db;
+
+  // Mount the auth middleware module
+  const { requireAuth, requireAdmin } = require('../../middleware/auth');
+
+  // Health check endpoint (should remain public)
+  app.get('/api/health', (req, res) => {
+    res.json({ status: 'ok' });
+  });
+
+  // Try to mount admin routes if they exist
+  try {
+    const adminRoutes = require('../../routes/admin');
+    app.use('/api/admin', requireAuth, requireAdmin, adminRoutes);
+  } catch (error) {
+    // Admin routes don't exist yet - this is expected for failing tests
+    // Create placeholder routes that will 404
+    app.use('/api/admin', requireAuth, requireAdmin, (req, res) => {
+      res.status(404).json({ error: 'Admin routes not implemented' });
+    });
+  }
+
+  return app;
+}
+
+/**
+ * Generate a valid JWT token for a test user
+ * @param {string|ObjectId} userId - The user's MongoDB _id
+ * @returns {string} JWT token
+ */
+function generateTestToken(userId) {
+  const secret = process.env.JWT_SECRET || 'test-jwt-secret-for-testing-only';
+  return jwt.sign(
+    { userId: userId.toString() },
+    secret,
+    { expiresIn: '7d' }
+  );
+}
+
+/**
+ * Create a test user document
+ * @param {Object} overrides - Fields to override in the default user
+ * @returns {Object} User document
+ */
+function createTestUser(overrides = {}) {
+  const now = new Date();
+  const uniqueId = `${Date.now()}-${++uniqueCounter}-${Math.random().toString(36).substr(2, 9)}`;
+  return {
+    _id: new ObjectId(),
+    googleId: `google-${uniqueId}`,
+    email: `test-${uniqueId}@example.com`,
+    name: 'Test User',
+    picture: 'https://example.com/photo.jpg',
+    role: 'user',
+    isActive: true,
+    loginCount: 1,
+    createdAt: now,
+    lastLoginAt: now,
+    disabledAt: null,
+    disabledBy: null,
+    ...overrides
+  };
+}
+
+/**
+ * Create an admin user document
+ * @param {Object} overrides - Fields to override in the default admin
+ * @returns {Object} Admin user document
+ */
+function createTestAdmin(overrides = {}) {
+  const uniqueId = `${Date.now()}-${++uniqueCounter}-${Math.random().toString(36).substr(2, 9)}`;
+  return createTestUser({
+    role: 'admin',
+    email: `admin-${uniqueId}@example.com`,
+    name: 'Test Admin',
+    ...overrides
+  });
+}
+
+/**
+ * Insert a user into the database
+ * @param {Db} db - MongoDB database instance
+ * @param {Object} user - User document to insert
+ * @returns {Promise<Object>} Inserted user with _id
+ */
+async function insertTestUser(db, user) {
+  const result = await db.collection('users').insertOne(user);
+  return { ...user, _id: result.insertedId };
+}
+
+/**
+ * Clean up test users from the database
+ * @param {Db} db - MongoDB database instance
+ */
+async function cleanupTestUsers(db) {
+  await db.collection('users').deleteMany({});
+}
+
+/**
+ * Clean up all test data from the database
+ * @param {Db} db - MongoDB database instance
+ */
+async function cleanupTestData(db) {
+  await Promise.all([
+    db.collection('users').deleteMany({}),
+    db.collection('user_activity').deleteMany({})
+  ]);
+}
+
+/**
+ * Create a test activity document
+ * @param {Object} overrides - Fields to override in the default activity
+ * @returns {Object} Activity document
+ */
+function createTestActivity(overrides = {}) {
+  const now = new Date();
+  return {
+    _id: new ObjectId(),
+    userId: new ObjectId(),
+    action: 'PAGE_VIEW',
+    metadata: { path: '/test' },
+    timestamp: now,
+    sessionId: `session-${Date.now()}`,
+    ...overrides
+  };
+}
+
+module.exports = {
+  createTestApp,
+  generateTestToken,
+  createTestUser,
+  createTestAdmin,
+  insertTestUser,
+  cleanupTestUsers,
+  cleanupTestData,
+  createTestActivity
+};