Fix incorrect time-zone in results after localization

Consider the following example using the canonical way to add zones to
datetime objects:

    >>> import pytz
    >>> import datetime
    >>> import zoneinfo
    >>> datetime.datetime(2023, 1, 1, tzinfo=pytz.timezone("America/Los_Angeles")).isoformat()
    '2023-01-01T00:00:00-07:53'
    >>> datetime.datetime(2023, 1, 1, tzinfo=zoneinfo.ZoneInfo("America/Los_Angeles")).isoformat()
    '2023-01-01T00:00:00-08:00'

pytz does eager timezone evaluation and uses the local-mean-time since
the instant in time is not known. It requires an additional `localize`
call to get the correct zone like so:

    >>> pytz.timezone("America/Los_Angeles").localize(datetime.datetime(2023, 1, 1)).isoformat()
    '2023-01-01T00:00:00-08:00'

This increases chances of introducing bugs when writing idiomatic
Python.

The only reason to use pytz was because it allowed to control what
happens with ambiguous datetimes but the standard library also allows
provides control over that since 3.9 (and is available as
backports.zoneinfo for older versions).

Author: john-bodley

setup.py

@@ -80,6 +80,7 @@
     python_requires='>=3.7',
     install_requires=[
         "backports.zoneinfo;python_version<'3.9'",
+        "python-dateutil",
         "pytz",
         "requests",
         "tzlocal",

tests/integration/test_dbapi_integration.py

@@ -15,8 +15,12 @@
 from decimal import Decimal
 from typing import Tuple
 
+try:
+    from zoneinfo import ZoneInfo
+except ModuleNotFoundError:
+    from backports.zoneinfo import ZoneInfo
+
 import pytest
-import pytz
 import requests
 from tzlocal import get_localzone_name  # type: ignore
 
@@ -234,7 +238,7 @@ def test_legacy_primitive_types_with_connection_and_cursor(
         assert rows[0][0] == Decimal('0.142857')
         assert rows[0][1] == date(2018, 1, 1)
         assert rows[0][2] == datetime(2019, 1, 1, tzinfo=timezone(timedelta(hours=1)))
-        assert rows[0][3] == datetime(2019, 1, 1, tzinfo=pytz.timezone('UTC'))
+        assert rows[0][3] == datetime(2019, 1, 1, tzinfo=ZoneInfo('UTC'))
         assert rows[0][4] == datetime(2019, 1, 1)
         assert rows[0][5] == time(0, 0, 0, 0)
     else:
@@ -338,7 +342,7 @@ def test_datetime_query_param(trino_connection):
 def test_datetime_with_utc_time_zone_query_param(trino_connection):
     cur = trino_connection.cursor()
 
-    params = datetime(2020, 1, 1, 16, 43, 22, 320000, tzinfo=pytz.timezone('UTC'))
+    params = datetime(2020, 1, 1, 16, 43, 22, 320000, tzinfo=ZoneInfo('UTC'))
 
     cur.execute("SELECT ?", params=(params,))
     rows = cur.fetchall()
@@ -364,7 +368,7 @@ def test_datetime_with_numeric_offset_time_zone_query_param(trino_connection):
 def test_datetime_with_named_time_zone_query_param(trino_connection):
     cur = trino_connection.cursor()
 
-    params = datetime(2020, 1, 1, 16, 43, 22, 320000, tzinfo=pytz.timezone('America/Los_Angeles'))
+    params = datetime(2020, 1, 1, 16, 43, 22, 320000, tzinfo=ZoneInfo('America/Los_Angeles'))
 
     cur.execute("SELECT ?", params=(params,))
     rows = cur.fetchall()
@@ -407,32 +411,24 @@ def test_datetimes_with_time_zone_in_dst_gap_query_param(trino_connection):
     cur = trino_connection.cursor()
 
     # This is a datetime that lies within a DST transition and not actually exists.
-    params = datetime(2021, 3, 28, 2, 30, 0, tzinfo=pytz.timezone('Europe/Brussels'))
+    params = datetime(2021, 3, 28, 2, 30, 0, tzinfo=ZoneInfo('Europe/Brussels'))
     with pytest.raises(trino.exceptions.TrinoUserError):
         cur.execute("SELECT ?", params=(params,))
         cur.fetchall()
 
 
-def test_doubled_datetimes(trino_connection):
-    # Trino doesn't distinguish between doubled datetimes that lie within a DST transition. See also
+@pytest.mark.parametrize('fold', [0, 1])
+def test_doubled_datetimes(trino_connection, fold):
+    # Trino doesn't distinguish between doubled datetimes that lie within a DST transition.
     # See also https://github.com/trinodb/trino/issues/5781
     cur = trino_connection.cursor()
 
-    params = pytz.timezone('US/Eastern').localize(datetime(2002, 10, 27, 1, 30, 0), is_dst=True)
+    params = datetime(2002, 10, 27, 1, 30, 0, tzinfo=ZoneInfo('US/Eastern'), fold=fold)
 
     cur.execute("SELECT ?", params=(params,))
     rows = cur.fetchall()
 
-    assert rows[0][0] == datetime(2002, 10, 27, 1, 30, 0, tzinfo=pytz.timezone('US/Eastern'))
-
-    cur = trino_connection.cursor()
-
-    params = pytz.timezone('US/Eastern').localize(datetime(2002, 10, 27, 1, 30, 0), is_dst=False)
-
-    cur.execute("SELECT ?", params=(params,))
-    rows = cur.fetchall()
-
-    assert rows[0][0] == datetime(2002, 10, 27, 1, 30, 0, tzinfo=pytz.timezone('US/Eastern'))
+    assert rows[0][0] == datetime(2002, 10, 27, 1, 30, 0, tzinfo=ZoneInfo('US/Eastern'))
 
 
 def test_date_query_param(trino_connection):
@@ -529,7 +525,7 @@ def test_time_query_param(trino_connection):
 def test_time_with_named_time_zone_query_param(trino_connection):
     cur = trino_connection.cursor()
 
-    params = time(16, 43, 22, 320000, tzinfo=pytz.timezone('Asia/Shanghai'))
+    params = time(16, 43, 22, 320000, tzinfo=ZoneInfo('Asia/Shanghai'))
 
     cur.execute("SELECT ?", params=(params,))
     rows = cur.fetchall()
@@ -693,7 +689,10 @@ def test_array_timestamp_query_param(trino_connection):
 def test_array_timestamp_with_timezone_query_param(trino_connection):
     cur = trino_connection.cursor()
 
-    params = [datetime(2020, 1, 1, 0, 0, 0, tzinfo=pytz.utc), datetime(2020, 1, 2, 0, 0, 0, tzinfo=pytz.utc)]
+    params = [
+        datetime(2020, 1, 1, 0, 0, 0, tzinfo=ZoneInfo('UTC')),
+        datetime(2020, 1, 2, 0, 0, 0, tzinfo=ZoneInfo('UTC')),
+    ]
 
     cur.execute("SELECT ?", params=(params,))
     rows = cur.fetchall()

tests/integration/test_types_integration.py

@@ -4,8 +4,12 @@
 from datetime import date, datetime, time, timedelta, timezone, tzinfo
 from decimal import Decimal
 
+try:
+    from zoneinfo import ZoneInfo
+except ModuleNotFoundError:
+    from backports.zoneinfo import ZoneInfo
+
 import pytest
-import pytz
 
 import trino
 from tests.integration.conftest import trino_version
@@ -729,7 +733,7 @@ def create_timezone(timezone_str: str) -> tzinfo:
         else:
             return timezone(-timedelta(hours=hours, minutes=minutes))
     else:
-        return pytz.timezone(timezone_str)
+        return ZoneInfo(timezone_str)
 
 
 def test_interval(trino_connection):

trino/client.py

@@ -51,21 +51,18 @@
 from time import sleep
 from typing import Any, Dict, Generic, List, Optional, Tuple, TypeVar, Union
 
-import pytz
+try:
+    from zoneinfo import ZoneInfo
+except ModuleNotFoundError:
+    from backports.zoneinfo import ZoneInfo
+
 import requests
-from pytz.tzinfo import BaseTzInfo
+from dateutil import tz
 from tzlocal import get_localzone_name  # type: ignore
 
 import trino.logging
 from trino import constants, exceptions
 
-try:
-    from zoneinfo import ZoneInfo  # type: ignore
-
-except ModuleNotFoundError:
-    from backports.zoneinfo import ZoneInfo  # type: ignore
-
-
 __all__ = ["ClientSession", "TrinoQuery", "TrinoRequest", "PROXIES"]
 
 logger = trino.logging.get_logger(__name__)
@@ -946,7 +943,7 @@ def _create_tzinfo(timezone_str: str) -> tzinfo:
             return timezone(-timedelta(hours=int(hours), minutes=int(minutes)))
         return timezone(timedelta(hours=int(hours), minutes=int(minutes)))
     else:
-        return pytz.timezone(timezone_str)
+        return ZoneInfo(timezone_str)
 
 
 def _fraction_to_decimal(fractional_str: str) -> Decimal:
@@ -996,8 +993,7 @@ def add_time_delta(self, time_delta: timedelta) -> PythonTemporalType:
     def normalize(self, value: PythonTemporalType) -> PythonTemporalType:
         """
             If `add_time_delta` results in value crossing DST boundaries, this method should
-            return a normalized version of the value to account for it, for example,
-            using `pytz.timezone.normalize`.
+            return a normalized version of the value to account for it.
         """
         return value
 
@@ -1041,7 +1037,7 @@ def new_instance(self, value: datetime, fraction: Decimal) -> TimestampWithTimeZ
         return TimestampWithTimeZone(value, fraction)
 
     def normalize(self, value: datetime) -> datetime:
-        if isinstance(self._whole_python_temporal_value.tzinfo, BaseTzInfo):
+        if tz.datetime_ambiguous(value):
             return self._whole_python_temporal_value.tzinfo.normalize(value)
         return value
 

trino/dbapi.py

@@ -25,7 +25,10 @@
 from typing import Any, Dict, List, NamedTuple, Optional  # NOQA for mypy types
 from urllib.parse import urlparse
 
-import pytz
+try:
+    from zoneinfo import ZoneInfo
+except ModuleNotFoundError:
+    from backports.zoneinfo import ZoneInfo
 
 import trino.client
 import trino.exceptions
@@ -425,8 +428,8 @@ def _format_prepared_param(self, param):
         if isinstance(param, datetime.datetime) and param.tzinfo is not None:
             datetime_str = param.strftime("%Y-%m-%d %H:%M:%S.%f")
             # named timezones
-            if hasattr(param.tzinfo, 'zone'):
-                return "TIMESTAMP '%s %s'" % (datetime_str, param.tzinfo.zone)
+            if isinstance(param.tzinfo, ZoneInfo):
+                return "TIMESTAMP '%s %s'" % (datetime_str, param.tzinfo.key)
             # offset-based timezones
             return "TIMESTAMP '%s %s'" % (datetime_str, param.tzinfo.tzname(param))
 
@@ -438,8 +441,8 @@ def _format_prepared_param(self, param):
         if isinstance(param, datetime.time) and param.tzinfo is not None:
             time_str = param.strftime("%H:%M:%S.%f")
             # named timezones
-            if hasattr(param.tzinfo, 'zone'):
-                utc_offset = datetime.datetime.now(pytz.timezone(param.tzinfo.zone)).strftime('%z')
+            if isinstance(param.tzinfo, ZoneInfo):
+                utc_offset = datetime.datetime.now(tz=param.tzinfo).strftime('%z')
                 return "TIME '%s %s:%s'" % (time_str, utc_offset[:3], utc_offset[3:])
             # offset-based timezones
             return "TIME '%s %s'" % (time_str, param.strftime('%Z')[3:])