In ServiceBus receiver set max_message_count to 1 for receive_messages (Azure#14939)

* In ServiceBus receiver set max_message_count to 1 for receive_messages

* Fix return type from merge conflict

* Allow servicebus receive_messages' max_messages_count to be None

* Set servicebus async receive_messages' max_message_count default to 1

* changelog, test and mypy update

* revert the internal _receive signature

Co-authored-by: Yunhao Ling <adam_ling@outlook.com>

Author: stefpiatek

sdk/servicebus/azure-servicebus/CHANGELOG.md

@@ -58,6 +58,7 @@ now raise more concrete exception other than `MessageSettleFailed` and `ServiceB
 * `ServiceBusMessage.amqp_annotated_message` has had its type renamed from `AMQPMessage` to `AMQPAnnotatedMessage`
 * `AutoLockRenewer` `timeout` parameter is renamed to `max_lock_renew_duration`
 * Attempting to autorenew a non-renewable message, such as one received in `ReceiveAndDelete` mode, or configure auto-autorenewal on a `ReceiveAndDelete` receiver, will raise a `ValueError`.
+* The default value of parameter `max_message_count` on `ServiceBusReceiver.receive_messages` is now `1` instead of `None` and will raise ValueError if the given value is less than or equal to 0.
 
 **BugFixes**
 

sdk/servicebus/azure-servicebus/azure/servicebus/_servicebus_receiver.py

@@ -482,8 +482,8 @@ def _from_connection_string(
             raise ValueError("Subscription name is missing for the topic. Please specify subscription_name.")
         return cls(**constructor_args)
 
-    def receive_messages(self, max_message_count=None, max_wait_time=None):
-        # type: (int, float) -> List[ServiceBusReceivedMessage]
+    def receive_messages(self, max_message_count=1, max_wait_time=None):
+        # type: (Optional[int], Optional[float]) -> List[ServiceBusReceivedMessage]
         """Receive a batch of messages at once.
 
         This approach is optimal if you wish to process multiple messages simultaneously, or
@@ -499,6 +499,7 @@ def receive_messages(self, max_message_count=None, max_wait_time=None):
 
         :param Optional[int] max_message_count: Maximum number of messages in the batch. Actual number
          returned will depend on prefetch_count and incoming stream rate.
+         Setting to None will fully depend on the prefetch config. The default value is 1.
         :param Optional[float] max_wait_time: Maximum time to wait in seconds for the first message to arrive.
          If no messages arrive, and no timeout is specified, this call will not return
          until the connection is closed. If specified, an no messages arrive within the
@@ -518,6 +519,8 @@ def receive_messages(self, max_message_count=None, max_wait_time=None):
         """
         if max_wait_time is not None and max_wait_time <= 0:
             raise ValueError("The max_wait_time must be greater than 0.")
+        if max_message_count is not None and max_message_count <= 0:
+            raise ValueError("The max_message_count must be greater than 0")
         self._check_live()
         messages = self._do_retryable_operation(
             self._receive,

sdk/servicebus/azure-servicebus/azure/servicebus/aio/_servicebus_receiver_async.py

@@ -481,7 +481,7 @@ def _from_connection_string(
 
     async def receive_messages(
         self,
-        max_message_count: Optional[int] = None,
+        max_message_count: Optional[int] = 1,
         max_wait_time: Optional[float] = None
     ) -> List[ServiceBusReceivedMessage]:
         """Receive a batch of messages at once.
@@ -499,6 +499,7 @@ async def receive_messages(
 
         :param Optional[int] max_message_count: Maximum number of messages in the batch. Actual number
          returned will depend on prefetch_count size and incoming stream rate.
+         Setting to None will fully depend on the prefetch config. The default value is 1.
         :param Optional[float] max_wait_time: Maximum time to wait in seconds for the first message to arrive.
          If no messages arrive, and no timeout is specified, this call will not return
          until the connection is closed. If specified, and no messages arrive within the
@@ -517,6 +518,8 @@ async def receive_messages(
         """
         if max_wait_time is not None and max_wait_time <= 0:
             raise ValueError("The max_wait_time must be greater than 0.")
+        if max_message_count is not None and max_message_count <= 0:
+            raise ValueError("The max_message_count must be greater than 0")
         self._check_live()
         messages = await self._do_retryable_operation(
             self._receive,

sdk/servicebus/azure-servicebus/tests/test_sessions.py

@@ -852,7 +852,7 @@ def test_session_schedule_multiple_messages(self, servicebus_namespace_connectio
                 count = 0
                 while len(messages) < 2 and count < 12:
                     receiver.session.renew_lock(timeout=None)
-                    messages = receiver.receive_messages(max_wait_time=15)
+                    messages.extend(receiver.receive_messages(max_wait_time=15))
                     time.sleep(5)
                     count += 1