Add series fields to audiobooks and update related logic

Introduces 'series' and 'seriesPart' fields to the Audiobook model and database schema. Updates API routes, file organization, and path template utilities to support series metadata. Enhances chapter merging logic, improves notification backend testing, and expands test coverage for admin and API routes.

tests/api/admin-notifications-test.routes.test.ts

@@ -4,9 +4,15 @@
  */
 
 import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { createPrismaMock } from '../helpers/prisma';
 
 let authRequest: any;
 
+const prismaMock = createPrismaMock();
+prismaMock.notificationBackend = {
+  findUnique: vi.fn(),
+} as any;
+
 const requireAuthMock = vi.hoisted(() => vi.fn());
 const requireAdminMock = vi.hoisted(() => vi.fn());
 const notificationServiceMock = vi.hoisted(() => ({
@@ -15,6 +21,10 @@ const notificationServiceMock = vi.hoisted(() => ({
   sendToBackend: vi.fn(),
 }));
 
+vi.mock('@/lib/db', () => ({
+  prisma: prismaMock,
+}));
+
 vi.mock('@/lib/middleware/auth', () => ({
   requireAuth: requireAuthMock,
   requireAdmin: requireAdminMock,
@@ -126,5 +136,62 @@ describe('Admin notifications test route', () => {
       expect(payload.success).toBe(true);
       expect(notificationServiceMock.encryptConfig).toHaveBeenCalledWith('pushover', testConfig.config);
     });
+
+    it('tests existing backend using backend ID', async () => {
+      const existingBackend = {
+        id: 'backend-1',
+        type: 'discord',
+        name: 'Discord - Admins',
+        config: { webhookUrl: 'iv:authTag:encryptedData', username: 'Bot' }, // Already encrypted
+        events: ['request_available'],
+        enabled: true,
+        createdAt: new Date(),
+        updatedAt: new Date(),
+      };
+
+      prismaMock.notificationBackend.findUnique.mockResolvedValue(existingBackend);
+      authRequest.json.mockResolvedValue({ backendId: 'backend-1' });
+      notificationServiceMock.sendToBackend.mockResolvedValue(undefined);
+
+      const { POST } = await import('@/app/api/admin/notifications/test/route');
+      const response = await POST({ json: authRequest.json } as any);
+      const payload = await response.json();
+
+      expect(payload.success).toBe(true);
+      expect(prismaMock.notificationBackend.findUnique).toHaveBeenCalledWith({
+        where: { id: 'backend-1' },
+      });
+      // Should use stored config directly, not encrypt again
+      expect(notificationServiceMock.encryptConfig).not.toHaveBeenCalled();
+      expect(notificationServiceMock.sendToBackend).toHaveBeenCalledWith(
+        'discord',
+        existingBackend.config,
+        expect.any(Object)
+      );
+    });
+
+    it('returns 404 if backend ID not found', async () => {
+      prismaMock.notificationBackend.findUnique.mockResolvedValue(null);
+      authRequest.json.mockResolvedValue({ backendId: 'nonexistent' });
+
+      const { POST } = await import('@/app/api/admin/notifications/test/route');
+      const response = await POST({ json: authRequest.json } as any);
+
+      expect(response.status).toBe(404);
+      const payload = await response.json();
+      expect(payload.error).toBe('NotFound');
+    });
+
+    it('returns validation error when payload is invalid', async () => {
+      authRequest.json.mockResolvedValue('bad-payload');
+
+      const { POST } = await import('@/app/api/admin/notifications/test/route');
+      const response = await POST({ json: authRequest.json } as any);
+      const payload = await response.json();
+
+      expect(response.status).toBe(400);
+      expect(payload.error).toBe('ValidationError');
+      expect(payload.details).toBeDefined();
+    });
   });
 });