fix(notifications): Add missing test notification endpoint (Issue #1002) (#1047)

The frontend test notification feature was calling /api/test-notifications/trigger,
but this endpoint didn't exist in the backend, causing a 404 HTML response that
failed JSON parsing with the error "JSON.parse: unexpected character at line 1 column 1".

Changes:
- Added triggerTestNotification service method to handle test notification creation
- Added triggerTestNotification controller method to handle the API request
- Registered POST /test-notifications/trigger route
- Implemented type mapping for all notification types (task_due_soon, task_overdue,
  defer_until, project_due_soon, project_overdue)
- Test notifications respect user notification preferences and send to enabled channels
- Returns notification details with sources (in-app, telegram) sent to

Fixes #1002

backend/modules/notifications/controller.js

@@ -81,6 +81,27 @@ const notificationsController = {
             next(error);
         }
     },
+
+    async triggerTestNotification(req, res, next) {
+        try {
+            const userId = requireUserId(req);
+            const { type } = req.body;
+
+            if (!type) {
+                return res
+                    .status(400)
+                    .json({ error: 'Notification type is required' });
+            }
+
+            const result = await notificationsService.triggerTestNotification(
+                userId,
+                type
+            );
+            res.json(result);
+        } catch (error) {
+            next(error);
+        }
+    },
 };
 
 module.exports = notificationsController;

backend/modules/notifications/routes.js

@@ -16,5 +16,9 @@ router.post(
     notificationsController.markAllAsRead
 );
 router.delete('/notifications/:id', notificationsController.dismiss);
+router.post(
+    '/test-notifications/trigger',
+    notificationsController.triggerTestNotification
+);
 
 module.exports = router;

backend/modules/notifications/service.js

@@ -60,6 +60,103 @@ class NotificationsService {
         await notification.dismiss();
         return { message: 'Notification dismissed successfully' };
     }
+
+    async triggerTestNotification(userId, testType) {
+        const { User, Notification } = require('../../models');
+        const {
+            shouldSendTelegramNotification,
+        } = require('../../utils/notificationPreferences');
+
+        const user = await User.findByPk(userId, {
+            attributes: [
+                'id',
+                'name',
+                'notification_preferences',
+                'telegram_bot_token',
+                'telegram_chat_id',
+            ],
+        });
+
+        if (!user) {
+            throw new NotFoundError('User not found');
+        }
+
+        const typeMapping = {
+            task_due_soon: {
+                backendType: 'task_due_soon',
+                preferenceKey: 'dueTasks',
+                title: 'Test: Task Due Soon',
+                message:
+                    'This is a test notification for tasks that are due within 24 hours',
+                data: { test: true, taskName: 'Sample Task' },
+            },
+            task_overdue: {
+                backendType: 'task_overdue',
+                preferenceKey: 'overdueTasks',
+                title: 'Test: Task Overdue',
+                message: 'This is a test notification for overdue tasks',
+                data: { test: true, taskName: 'Sample Overdue Task' },
+            },
+            defer_until: {
+                backendType: 'task_due_soon',
+                preferenceKey: 'deferUntil',
+                title: 'Test: Task Now Active',
+                message:
+                    'This is a test notification for tasks that are now available to work on',
+                data: {
+                    test: true,
+                    taskName: 'Sample Deferred Task',
+                    reason: 'defer_until_reached',
+                },
+            },
+            project_due_soon: {
+                backendType: 'project_due_soon',
+                preferenceKey: 'dueProjects',
+                title: 'Test: Project Due Soon',
+                message:
+                    'This is a test notification for projects that are due within 24 hours',
+                data: { test: true, projectName: 'Sample Project' },
+            },
+            project_overdue: {
+                backendType: 'project_overdue',
+                preferenceKey: 'overdueProjects',
+                title: 'Test: Project Overdue',
+                message: 'This is a test notification for overdue projects',
+                data: { test: true, projectName: 'Sample Overdue Project' },
+            },
+        };
+
+        const config = typeMapping[testType];
+        if (!config) {
+            throw new Error(`Invalid test type: ${testType}`);
+        }
+
+        const sources = [];
+        if (shouldSendTelegramNotification(user, config.preferenceKey)) {
+            sources.push('telegram');
+        }
+
+        const notification = await Notification.createNotification({
+            userId: user.id,
+            type: config.backendType,
+            title: config.title,
+            message: config.message,
+            data: config.data,
+            sources,
+            sentAt: new Date(),
+        });
+
+        return {
+            notification: {
+                id: notification.id,
+                type: notification.type,
+                title: notification.title,
+                message: notification.message,
+                sources: notification.sources,
+            },
+            message: 'Test notification created successfully',
+        };
+    }
 }
 
 module.exports = new NotificationsService();