feat: add notification badge counts

src/modules/notifications/notifications.service.spec.ts

@@ -1,7 +1,19 @@
 import { NotFoundException } from '@nestjs/common';
+import { plainToInstance } from 'class-transformer';
+import { validate } from 'class-validator';
+import { NotificationUnreadCountQueryDto } from './dto/notification-query.dto';
 import { NotificationsService } from './notifications.service';
 
 describe('NotificationsService', () => {
+  it('rejects invalid unread-count category through DTO validation', async () => {
+    const dto = plainToInstance(NotificationUnreadCountQueryDto, { category: 'badges' });
+
+    const errors = await validate(dto);
+
+    expect(errors.length).toBeGreaterThan(0);
+    expect(errors[0].property).toBe('category');
+  });
+
   it('creates mention notifications with mention type', async () => {
     const notificationsRepository = {
       create: jest.fn().mockResolvedValue({ toJSON: () => ({ _id: 'notification-1' }) }),
@@ -107,6 +119,139 @@ describe('NotificationsService', () => {
     expect(notificationsRepository.countUnread).toHaveBeenCalledWith('507f1f77bcf86cd799439011');
   });
 
+  it('returns total unread count without category for backward compatibility', async () => {
+    const notificationsRepository = {
+      countUnread: jest.fn().mockResolvedValue(10),
+    };
+    const notificationsGateway = {};
+
+    const service = new NotificationsService(
+      notificationsRepository as any,
+      notificationsGateway as any,
+    );
+
+    await expect(service.getUnreadCountByCategory('507f1f77bcf86cd799439011')).resolves.toEqual({
+      unreadCount: 10,
+    });
+    expect(notificationsRepository.countUnread).toHaveBeenCalledWith('507f1f77bcf86cd799439011');
+  });
+
+  it('returns unread count for interactions category only', async () => {
+    const notificationsRepository = {
+      countUnreadByFilter: jest.fn().mockResolvedValue(4),
+    };
+    const notificationsGateway = {};
+
+    const service = new NotificationsService(
+      notificationsRepository as any,
+      notificationsGateway as any,
+    );
+
+    await expect(
+      service.getUnreadCountByCategory('507f1f77bcf86cd799439011', 'interactions'),
+    ).resolves.toEqual({
+      unreadCount: 4,
+      category: 'interactions',
+    });
+    expect(notificationsRepository.countUnreadByFilter).toHaveBeenCalledWith(
+      '507f1f77bcf86cd799439011',
+      {
+        type: {
+          $in: [
+            'like',
+            'comment',
+            'reply',
+            'mention',
+            'save',
+            'share',
+            'collaboration_request',
+            'system',
+          ],
+        },
+      },
+    );
+  });
+
+  it('returns unread count for messages category only', async () => {
+    const notificationsRepository = {
+      countUnreadByFilter: jest.fn().mockResolvedValue(3),
+    };
+    const notificationsGateway = {};
+
+    const service = new NotificationsService(
+      notificationsRepository as any,
+      notificationsGateway as any,
+    );
+
+    await expect(
+      service.getUnreadCountByCategory('507f1f77bcf86cd799439011', 'messages'),
+    ).resolves.toEqual({
+      unreadCount: 3,
+      category: 'messages',
+    });
+    expect(notificationsRepository.countUnreadByFilter).toHaveBeenCalledWith(
+      '507f1f77bcf86cd799439011',
+      { type: { $in: ['message'] } },
+    );
+  });
+
+  it('returns unread count for follow requests category only', async () => {
+    const notificationsRepository = {
+      countUnreadByFilter: jest.fn().mockResolvedValue(2),
+    };
+    const notificationsGateway = {};
+
+    const service = new NotificationsService(
+      notificationsRepository as any,
+      notificationsGateway as any,
+    );
+
+    await expect(
+      service.getUnreadCountByCategory('507f1f77bcf86cd799439011', 'follow_requests'),
+    ).resolves.toEqual({
+      unreadCount: 2,
+      category: 'follow_requests',
+    });
+    expect(notificationsRepository.countUnreadByFilter).toHaveBeenCalledWith(
+      '507f1f77bcf86cd799439011',
+      {
+        type: {
+          $in: ['follow_request', 'follow_request_approved', 'follow_request_rejected'],
+        },
+      },
+    );
+  });
+
+  it('returns grouped unread counts for badge hydration', async () => {
+    const notificationsRepository = {
+      countUnread: jest.fn().mockResolvedValue(10),
+      countUnreadByFilter: jest
+        .fn()
+        .mockResolvedValueOnce(4)
+        .mockResolvedValueOnce(3)
+        .mockResolvedValueOnce(1)
+        .mockResolvedValueOnce(2)
+        .mockResolvedValueOnce(1)
+        .mockResolvedValueOnce(0),
+    };
+    const notificationsGateway = {};
+
+    const service = new NotificationsService(
+      notificationsRepository as any,
+      notificationsGateway as any,
+    );
+
+    await expect(service.getUnreadCounts('507f1f77bcf86cd799439011')).resolves.toEqual({
+      total: 10,
+      interactions: 4,
+      messages: 3,
+      follows: 1,
+      followRequests: 2,
+      collaboration: 1,
+      system: 0,
+    });
+  });
+
   it('filters notifications by interactions category', async () => {
     const notificationsRepository = {
       findMine: jest.fn().mockResolvedValue([]),