Fix issue #1011 with timezone conversion (from Windows timezones to IANA ones) using the python 3.9 ZoneInfo objects

Author: Alejandro Casanovas

O365/connection.py

@@ -14,7 +14,7 @@
 from requests_oauthlib import OAuth2Session
 from stringcase import pascalcase, camelcase, snakecase
 from tzlocal import get_localzone
-from zoneinfo import ZoneInfoNotFoundError
+from zoneinfo import ZoneInfoNotFoundError, ZoneInfo
 from .utils import ME_RESOURCE, BaseTokenBackend, FileSystemTokenBackend, Token
 import datetime as dt
 
@@ -96,13 +96,19 @@ def __init__(self, *, protocol_url=None, api_version=None,
         self.default_resource = default_resource or ME_RESOURCE
         self.use_default_casing = True if casing_function is None else False
         self.casing_function = casing_function or camelcase
-        if timezone and isinstance(timezone, str):
-            timezone = dt.timezone(timezone)
-        try:
-            self.timezone = timezone or get_localzone() 
-        except ZoneInfoNotFoundError as e:
-            log.debug('Timezone not provided and the local timezone could not be found. Default to UTC.')
-            self.timezone = dt.timezone.utc
+        if timezone:
+            if isinstance(timezone, str):
+                # convert string to ZoneInfo
+                try:
+                    timezone = ZoneInfo(timezone)
+                except ZoneInfoNotFoundError:
+                    log.debug(f'Timezone {timezone} could not be found. Will default to UTC.')
+                    timezone = ZoneInfo('UTC')
+            else:
+                if not isinstance(timezone, ZoneInfo):
+                    raise ValueError(f'The timezone parameter must be either a string or a valid ZoneInfo instance.')
+        # get_localzone() from tzlocal will try to get the system local timezone and if not will return UTC
+        self.timezone = timezone or get_localzone()
         self.max_top_value = 500  # Max $top parameter value
 
         # define any keyword that can be different in this protocol

O365/utils/utils.py

@@ -1,9 +1,8 @@
 import datetime as dt
-from zoneinfo import ZoneInfoNotFoundError
 import logging
 from collections import OrderedDict
 from enum import Enum
-import zoneinfo
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
 from dateutil.parser import parse
 from stringcase import snakecase
@@ -431,7 +430,7 @@ def _parse_date_time_time_zone(self, date_time_time_zone, is_all_day=False):
         local_tz = self.protocol.timezone
         if isinstance(date_time_time_zone, dict):
             try:
-                timezone = zoneinfo.ZoneInfo(
+                timezone = ZoneInfo(
                     get_iana_tz(date_time_time_zone.get(self._cc('timeZone'), 'UTC')))
             except ZoneInfoNotFoundError:
                 timezone = local_tz

O365/utils/windows_tz.py

@@ -2,7 +2,7 @@
 Mapping from iana timezones to windows timezones and vice versa
 """
 from datetime import tzinfo
-from zoneinfo import ZoneInfoNotFoundError
+from zoneinfo import ZoneInfoNotFoundError, ZoneInfo
 
 # noinspection SpellCheckingInspection
 IANA_TO_WIN = {
@@ -628,16 +628,15 @@ def get_iana_tz(windows_tz):
     return timezone
 
 
-def get_windows_tz(iana_tz):
+def get_windows_tz(iana_tz: ZoneInfo) -> str:
     """ Returns a valid windows TimeZone from a given pytz TimeZone
     (Iana/Olson Timezones)
     Note: Windows Timezones are SHIT!... no ... really THEY ARE
     HOLY FUCKING SHIT!.
     """
     timezone = IANA_TO_WIN.get(
-        iana_tz.zone if isinstance(iana_tz, tzinfo) else iana_tz)
+        iana_tz.key if isinstance(iana_tz, tzinfo) else iana_tz)
     if timezone is None:
-        raise ZoneInfoNotFoundError(
-            "Can't find Iana TimeZone " + iana_tz.zone)
+        raise ZoneInfoNotFoundError(f"Can't find Iana timezone {iana_tz.key}")
 
     return timezone