Replace UTC_Now() workaround with MSRest.UTC (#13498)

* use msrest.serialization utc instead of custom implementation

* update reference for utc

Co-authored-by: Andy Gee <angee@microsoft.com>

sdk/servicebus/azure-servicebus/azure/servicebus/_common/utils.py

@@ -11,100 +11,89 @@
 import platform
 import time
 from typing import Optional, Dict, Tuple
+from msrest.serialization import UTC
+
 try:
     from urlparse import urlparse
 except ImportError:
     from urllib.parse import urlparse
 
 from uamqp import authentication, types
 
-from ..exceptions import ServiceBusError
 from .._version import VERSION
 from .constants import (
     JWT_TOKEN_SCOPE,
     TOKEN_TYPE_JWT,
     TOKEN_TYPE_SASTOKEN,
     DEAD_LETTER_QUEUE_SUFFIX,
     TRANSFER_DEAD_LETTER_QUEUE_SUFFIX,
-    USER_AGENT_PREFIX
+    USER_AGENT_PREFIX,
 )
 
 _log = logging.getLogger(__name__)
 
 
-class UTC(datetime.tzinfo):
-    """Time Zone info for handling UTC"""
-
-    def utcoffset(self, dt):
-        """UTF offset for UTC is 0."""
-        return datetime.timedelta(0)
-
-    def tzname(self, dt):
-        """Timestamp representation."""
-        return "Z"
-
-    def dst(self, dt):
-        """No daylight saving for UTC."""
-        return datetime.timedelta(hours=1)
-
-
-try:
-    from datetime import timezone  # pylint: disable=ungrouped-imports
-
-    TZ_UTC = timezone.utc  # type: ignore
-except ImportError:
-    TZ_UTC = UTC()  # type: ignore
-
-
 def utc_from_timestamp(timestamp):
-    return datetime.datetime.fromtimestamp(timestamp, tz=TZ_UTC)
+    return datetime.datetime.fromtimestamp(timestamp, tz=UTC())
 
 
 def utc_now():
-    return datetime.datetime.now(tz=TZ_UTC)
+    return datetime.datetime.now(UTC())
 
 
 # This parse_conn_str is used for mgmt, the other in base_handler for handlers.  Should be unified.
 def parse_conn_str(conn_str):
     # type: (str) -> Tuple[str, Optional[str], Optional[str], str, Optional[str], Optional[int]]
-    endpoint = ''
-    shared_access_key_name = None # type: Optional[str]
-    shared_access_key = None # type: Optional[str]
-    entity_path = ''
+    endpoint = ""
+    shared_access_key_name = None  # type: Optional[str]
+    shared_access_key = None  # type: Optional[str]
+    entity_path = ""
     shared_access_signature = None  # type: Optional[str]
-    shared_access_signature_expiry = None # type: Optional[int]
-    for element in conn_str.split(';'):
-        key, _, value = element.partition('=')
-        if key.lower() == 'endpoint':
-            endpoint = value.rstrip('/')
-        elif key.lower() == 'sharedaccesskeyname':
+    shared_access_signature_expiry = None  # type: Optional[int]
+    for element in conn_str.split(";"):
+        key, _, value = element.partition("=")
+        if key.lower() == "endpoint":
+            endpoint = value.rstrip("/")
+        elif key.lower() == "sharedaccesskeyname":
             shared_access_key_name = value
-        elif key.lower() == 'sharedaccesskey':
+        elif key.lower() == "sharedaccesskey":
             shared_access_key = value
-        elif key.lower() == 'entitypath':
+        elif key.lower() == "entitypath":
             entity_path = value
         elif key.lower() == "sharedaccesssignature":
             shared_access_signature = value
             try:
                 # Expiry can be stored in the "se=<timestamp>" clause of the token. ('&'-separated key-value pairs)
                 # type: ignore
-                shared_access_signature_expiry = int(shared_access_signature.split('se=')[1].split('&')[0])
-            except (IndexError, TypeError, ValueError): # Fallback since technically expiry is optional.
+                shared_access_signature_expiry = int(
+                    shared_access_signature.split("se=")[1].split("&")[0]
+                )
+            except (
+                IndexError,
+                TypeError,
+                ValueError,
+            ):  # Fallback since technically expiry is optional.
                 # An arbitrary, absurdly large number, since you can't renew.
                 shared_access_signature_expiry = int(time.time() * 2)
-    if not (all((endpoint, shared_access_key_name, shared_access_key)) or all((endpoint, shared_access_signature))) \
-        or all((shared_access_key_name, shared_access_signature)): # this latter clause since we don't accept both
+    if not (
+        all((endpoint, shared_access_key_name, shared_access_key))
+        or all((endpoint, shared_access_signature))
+    ) or all(
+        (shared_access_key_name, shared_access_signature)
+    ):  # this latter clause since we don't accept both
         raise ValueError(
             "Invalid connection string. Should be in the format: "
             "Endpoint=sb://<FQDN>/;SharedAccessKeyName=<KeyName>;SharedAccessKey=<KeyValue>"
             "\nWith alternate option of providing SharedAccessSignature instead of SharedAccessKeyName and Key"
         )
-    return (endpoint,
-            str(shared_access_key_name) if shared_access_key_name else None,
-            str(shared_access_key) if shared_access_key else None,
-            entity_path,
-            str(shared_access_signature) if shared_access_signature else None,
-            shared_access_signature_expiry)
+    return (
+        endpoint,
+        str(shared_access_key_name) if shared_access_key_name else None,
+        str(shared_access_key) if shared_access_key else None,
+        entity_path,
+        str(shared_access_signature) if shared_access_signature else None,
+        shared_access_signature_expiry,
+    )
 
 
 def build_uri(address, entity):
@@ -123,7 +112,8 @@ def create_properties(user_agent=None):
     Format the properties with which to instantiate the connection.
     This acts like a user agent over HTTP.
 
-    :param str user_agent: If specified, this will be added in front of the built-in user agent string.
+    :param str user_agent: If specified,
+    this will be added in front of the built-in user agent string.
 
     :rtype: dict
     """
@@ -189,23 +179,27 @@ def create_authentication(client):
 
 
 def generate_dead_letter_entity_name(
-        queue_name=None,
-        topic_name=None,
-        subscription_name=None,
-        transfer_deadletter=False
+    queue_name=None, topic_name=None, subscription_name=None, transfer_deadletter=False
 ):
-    entity_name = queue_name if queue_name else (topic_name + "/Subscriptions/" + subscription_name)
+    entity_name = (
+        queue_name
+        if queue_name
+        else (topic_name + "/Subscriptions/" + subscription_name)
+    )
     entity_name = "{}{}".format(
         entity_name,
-        TRANSFER_DEAD_LETTER_QUEUE_SUFFIX if transfer_deadletter else DEAD_LETTER_QUEUE_SUFFIX
+        TRANSFER_DEAD_LETTER_QUEUE_SUFFIX
+        if transfer_deadletter
+        else DEAD_LETTER_QUEUE_SUFFIX,
     )
 
     return entity_name
 
 
 def transform_messages_to_sendable_if_needed(messages):
     """
-    This method is to convert single/multiple received messages to sendable messages to enable message resending.
+    This method is to convert single/multiple received messages
+    to sendable messages to enable message resending.
     """
     # pylint: disable=protected-access
     try: