Fix time zone issue for date function

Author: Peng Ren

pymongosql/sql/projection_functions.py

@@ -2,7 +2,7 @@
 import logging
 import re
 from abc import ABC, abstractmethod
-from datetime import date, datetime
+from datetime import date, datetime, timezone
 from typing import Any, List, Optional, Tuple
 
 from bson import Timestamp
@@ -115,7 +115,7 @@ def extract_column_and_format(self, text: str) -> Tuple[str, Optional[str]]:
         return "", None
 
     def convert_value(self, value: Any, format_param: Optional[str] = None) -> Any:
-        """Convert to BSON Timestamp"""
+        """Convert to BSON Timestamp using UTC for consistency"""
         if value is None:
             return None
 
@@ -130,33 +130,39 @@ def convert_value(self, value: Any, format_param: Optional[str] = None) -> Any:
             # Try ISO format first
             try:
                 dt = datetime.fromisoformat(value)
+                # Use UTC if no timezone info
+                if dt.tzinfo is None:
+                    dt = dt.replace(tzinfo=timezone.utc)
                 timestamp_int = int(dt.timestamp())
                 return Timestamp(timestamp_int, 0)
             except (ValueError, TypeError):
                 pass
 
-            # Try date-only format (YYYY-MM-DD)
+            # Try date-only format (YYYY-MM-DD) - treat as UTC
             if re.match(r"^\d{4}-\d{2}-\d{2}$", value):
                 try:
                     dt = datetime.strptime(value, "%Y-%m-%d")
+                    dt = dt.replace(tzinfo=timezone.utc)  # Treat as UTC
                     timestamp_int = int(dt.timestamp())
                     return Timestamp(timestamp_int, 0)
                 except ValueError:
                     pass
 
-            # Try custom format if provided
+            # Try custom format if provided - treat as UTC
             if format_param:
                 try:
                     dt = datetime.strptime(value, format_param)
+                    dt = dt.replace(tzinfo=timezone.utc)  # Treat as UTC
                     timestamp_int = int(dt.timestamp())
                     return Timestamp(timestamp_int, 0)
                 except ValueError:
                     pass
 
-            # Try common formats
+            # Try common formats - treat as UTC
             for fmt in ["%Y-%m-%dT%H:%M:%SZ", "%Y-%m-%d %H:%M:%S", "%Y-%m-%d", "%d-%m-%Y", "%m/%d/%Y"]:
                 try:
                     dt = datetime.strptime(value, fmt)
+                    dt = dt.replace(tzinfo=timezone.utc)  # Treat as UTC
                     timestamp_int = int(dt.timestamp())
                     return Timestamp(timestamp_int, 0)
                 except ValueError:

tests/test_projection_functions.py

@@ -2,7 +2,7 @@
 """Tests for projection functions"""
 
 import re
-from datetime import date, datetime
+from datetime import date, datetime, timezone
 
 from bson import Timestamp
 
@@ -202,7 +202,14 @@ def test_convert_iso_date_string(self):
         func = TimestampFunction()
         result = func.convert_value("2025-01-15")
         assert isinstance(result, Timestamp)
-        assert result.time == 1736917200  # Unix timestamp for 2025-01-15 00:00:00 UTC
+        # Verify the timestamp represents 2025-01-15 00:00:00 UTC
+        # Use UTC explicitly for timezone-independent validation (Windows/Unix compatible)
+        dt = datetime.fromtimestamp(result.time, tz=timezone.utc)
+        assert dt.year == 2025
+        assert dt.month == 1
+        assert dt.day == 15
+        assert dt.hour == 0
+        assert dt.minute == 0
 
     def test_convert_iso_datetime_string(self):
         """Test conversion from ISO datetime strings"""