tests/test_gmail_service.py

import unittest
from unittest.mock import MagicMock, patch
from services.email_service import GmailService

class TestGmailService(unittest.TestCase):

    @patch('services.email_service.build')
    @patch('services.email_service.Credentials')
    def test_send_email_success(self, mock_credentials, mock_build):
        # Mock the service and its methods
        mock_service = MagicMock()
        mock_build.return_value = mock_service
        
        # Mock the send method
        mock_messages = mock_service.users.return_value.messages.return_value
        mock_messages.send.return_value.execute.return_value = {'id': '12345'}

        # Initialize service
        service = GmailService()
        service.client_id = "dummy_id"
        service.client_secret = "dummy_secret"
        service.refresh_token = "dummy_token"
        
        # Test authenticate
        self.assertTrue(service.authenticate())
        
        # Test send_email
        result = service.send_email("test@example.com", "Test Subject", "Test Body")
        self.assertTrue(result)
        
        # Verify calls
        mock_messages.send.assert_called_once()

    def test_missing_credentials(self):
        service = GmailService()
        # Ensure credentials are None
        service.client_id = None
        
        self.assertFalse(service.authenticate())

if __name__ == '__main__':
    unittest.main()