Implement Authentication Database Schema with Prisma ORM

__tests__/db/schema.test.ts

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+import { describe, expect, it, beforeAll, afterAll } from 'vitest'
+import { PrismaClient } from '@prisma/client'
+import { execSync } from 'child_process'
+
+const prisma = new PrismaClient()
+
+beforeAll(async () => {
+  // Run database migrations before tests
+  try {
+    execSync('npx prisma migrate dev --name init_test_schema', { stdio: 'inherit' })
+  } catch (error) {
+    console.error('Migration failed:', error)
+    throw error
+  }
+})
+
+afterAll(async () => {
+  // Clean up after tests
+  await prisma.$disconnect()
+})
+
+describe('Authentication Database Schema', () => {
+  it('should create a user with required fields', async () => {
+    const user = await prisma.user.create({
+      data: {
+        email: 'test@example.com',
+        passwordHash: 'hashed_password_placeholder',
+      }
+    })
+
+    expect(user).toBeDefined()
+    expect(user.email).toBe('test@example.com')
+    expect(user.createdAt).toBeDefined()
+  })
+
+  it('should prevent duplicate email addresses', async () => {
+    await prisma.user.create({
+      data: {
+        email: 'unique@example.com',
+        passwordHash: 'hashed_password_placeholder',
+      }
+    })
+
+    await expect(prisma.user.create({
+      data: {
+        email: 'unique@example.com',
+        passwordHash: 'another_hashed_password',
+      }
+    })).rejects.toThrow()
+  })
+
+  it('should create a saved job for a user', async () => {
+    const user = await prisma.user.create({
+      data: {
+        email: 'saveduser@example.com',
+        passwordHash: 'hashed_password_placeholder',
+      }
+    })
+
+    const savedJob = await prisma.savedJob.create({
+      data: {
+        userId: user.id,
+        jobId: 'job123',
+        jobTitle: 'Software Engineer',
+        companyName: 'Tech Corp'
+      }
+    })
+
+    expect(savedJob).toBeDefined()
+    expect(savedJob.jobTitle).toBe('Software Engineer')
+  })
+})

lib/db/prisma.ts

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+// Singleton Prisma Client to prevent multiple instances
+
+import { PrismaClient } from '@prisma/client'
+
+const globalForPrisma = global as unknown as { prisma: PrismaClient }
+
+export const prisma =
+  globalForPrisma.prisma ||
+  new PrismaClient({
+    log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error'],
+  })
+
+if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma