Address review feedback: Improve UTC compatibility implementation

- Enhance datetime_compat.py documentation
- Add edge case tests for UTC timezone handling
- Update mock patching in tests
- Fix utcnow usage in sqlite.py

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/agent_test.py

@@ -917,7 +917,7 @@ def test_tool_result_as_answer_is_the_final_answer_for_the_agent():
 
 @pytest.mark.vcr(filter_headers=["authorization"])
 def test_tool_usage_information_is_appended_to_agent():
-    from datetime import datetime
+    from datetime import datetime, timezone
 
     from crewai.tools import BaseTool
     from crewai.utilities.datetime_compat import UTC
@@ -930,7 +930,7 @@ def test_tool_usage_information_is_appended_to_agent():
             return "Howdy!"
 
     fixed_datetime = datetime(2025, 2, 10, 12, 0, 0, tzinfo=UTC)
-    with patch("crewai.tools.tool_usage.datetime") as mock_datetime:
+    with patch("crewai.tools.tool_usage.datetime", autospec=True) as mock_datetime:
         mock_datetime.now.return_value = fixed_datetime
         mock_datetime.fromtimestamp = datetime.fromtimestamp
         mock_datetime.side_effect = lambda *args, **kw: datetime(*args, **kw)

tests/utilities/test_datetime_compat.py

@@ -1,5 +1,5 @@
 """Test datetime compatibility module."""
-from datetime import timezone
+from datetime import datetime, timedelta, timezone
 
 from crewai.utilities.datetime_compat import UTC
 
@@ -9,6 +9,27 @@ def test_utc_timezone_compatibility():
     assert UTC == timezone.utc
     assert UTC.tzname(None) == "UTC"
     # Verify it works with datetime.now()
-    from datetime import datetime
     dt = datetime.now(UTC)
     assert dt.tzinfo == timezone.utc
+
+
+def test_utc_timezone_edge_cases():
+    """Test UTC timezone handling in edge cases."""
+    # Test with leap year
+    leap_date = datetime(2024, 2, 29, tzinfo=UTC)
+    assert leap_date.tzinfo == timezone.utc
+    
+    # Test DST transition dates
+    dst_date = datetime(2024, 3, 10, 2, 0, tzinfo=UTC)  # US DST start
+    assert dst_date.tzinfo == timezone.utc
+    
+    # Test with minimum/maximum dates
+    min_date = datetime.min.replace(tzinfo=UTC)
+    max_date = datetime.max.replace(tzinfo=UTC)
+    assert min_date.tzinfo == timezone.utc
+    assert max_date.tzinfo == timezone.utc
+    
+    # Test timezone offset calculations
+    dt = datetime(2024, 1, 1, tzinfo=UTC)
+    offset = dt.utcoffset()
+    assert offset == timedelta(0)  # UTC should always have zero offset