diff --git a/tests/unit/server.test.ts b/tests/unit/server.test.ts
index 33bab3f..85e48c9 100644
--- a/tests/unit/server.test.ts
+++ b/tests/unit/server.test.ts
@@ -54,8 +54,8 @@ describe('WebhookServer', () => {
       { event: 'messages.upsert', instance: null }
     ];
 
-    for (const payload of invalidPayloads) {
-      const request = createTestRequest(payload);
+    for (const invalidPayload of invalidPayloads) {
+      const request = createTestRequest(invalidPayload);
       const response = await WebhookServer.handleRequest(request);
       expect(response.status).toBe(400);
     }
@@ -518,4 +518,87 @@ describe('WebhookServer', () => {
     expect(response.status).toBe(200);
     expect(mockAdd).not.toHaveBeenCalled();
   });
+
+  // New tests for user validation
+  describe('User validation in handleMessageUpsert', () => {
+    let mockEnsureUserExists: any;
+    let consoleSpy: any;
+
+    beforeEach(() => {
+      mockEnsureUserExists = mock(() => '1234567890');
+      // Mock the function in the module
+      const dbModule = await import('../../src/db');
+      dbModule.ensureUserExists = mockEnsureUserExists;
+
+      consoleSpy = mock(() => {});
+      console.log = consoleSpy;
+    });
+
+    afterEach(() => {
+      mockEnsureUserExists.mockRestore();
+      consoleSpy.mockRestore();
+    });
+
+    test('should proceed with valid user', async () => {
+      mockEnsureUserExists.mockReturnValue('1234567890');
+      const payload = {
+        event: 'messages.upsert',
+        instance: 'test-instance',
+        data: {
+          key: {
+            remoteJid: 'group-id@g.us',
+            participant: '1234567890@s.whatsapp.net'
+          },
+          message: { conversation: '/tarea nueva Test' }
+        }
+      };
+      const request = createTestRequest(payload);
+      const response = await WebhookServer.handleRequest(request);
+      expect(response.status).toBe(200);
+      expect(mockEnsureUserExists).toHaveBeenCalledWith('1234567890@s.whatsapp.net');
+      expect(mockAdd).toHaveBeenCalled();
+    });
+
+    test('should ignore message if user validation fails', async () => {
+      mockEnsureUserExists.mockReturnValue(null);
+      const payload = {
+        event: 'messages.upsert',
+        instance: 'test-instance',
+        data: {
+          key: {
+            remoteJid: 'group-id@g.us',
+            participant: 'invalid-user@s.whatsapp.net'
+          },
+          message: { conversation: '/tarea nueva Test' }
+        }
+      };
+      const request = createTestRequest(payload);
+      const response = await WebhookServer.handleRequest(request);
+      expect(response.status).toBe(200);
+      expect(mockEnsureUserExists).toHaveBeenCalledWith('invalid-user@s.whatsapp.net');
+      expect(mockAdd).not.toHaveBeenCalled();
+      expect(consoleSpy).toHaveBeenCalledWith('⚠️ Failed to ensure user exists, ignoring message');
+    });
+
+    test('should handle database errors during user validation', async () => {
+      mockEnsureUserExists.mockImplementation(() => { throw new Error('DB error'); });
+      const payload = {
+        event: 'messages.upsert',
+        instance: 'test-instance',
+        data: {
+          key: {
+            remoteJid: 'group-id@g.us',
+            participant: '1234567890@s.whatsapp.net'
+          },
+          message: { conversation: '/tarea nueva Test' }
+        }
+      };
+      const request = createTestRequest(payload);
+      const response = await WebhookServer.handleRequest(request);
+      expect(response.status).toBe(200);
+      expect(mockEnsureUserExists).toHaveBeenCalledWith('1234567890@s.whatsapp.net');
+      expect(mockAdd).not.toHaveBeenCalled();
+      expect(consoleSpy).toHaveBeenCalledWith('⚠️ Failed to ensure user exists, ignoring message');
+    });
+  });
 });