[ServiceBus] Graceful noops for methods taking empty lists. (#15286)

Make send_messages, schedule_messages, cancel_scheduled_messages, and receive_deferred_messages gracefully no-op when provided an empty list or empty batch (where appropriate).  Adds tests and changelog notes for these scenarios.  Closes #15211

sdk/servicebus/azure-servicebus/CHANGELOG.md

@@ -4,14 +4,12 @@
 
 **Breaking Changes**
 
-* `ServiceBusSender` and `ServiceBusReceiver` are no longer reusable and will raise `ValueError` when trying to operate on a closed handler.
+* `ServiceBusSender` and `ServiceBusReceiver` are no more reusable and will raise `ValueError` when trying to operate on a closed handler.
+* `send_messages`, `schedule_messages`, `cancel_scheduled_messages` and `receive_deferred_messages` now performs a no-op rather than raising a `ValueError` if provided an empty list of messages or an empty batch.
 
 **BugFixes**
 
 * FQDNs and Connection strings are now supported even with strippable whitespace or protocol headers (e.g. 'sb://').
-
-**Bug Fixes**
-
 * Using parameter `auto_lock_renewer` on a sessionful receiver alongside `ReceiveMode.ReceiveAndDelete` will no longer fail during receipt due to failure to register the message with the renewer.
 
 ## 7.0.0b8 (2020-11-05)

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

@@ -555,8 +555,8 @@ def receive_deferred_messages(self, sequence_numbers, **kwargs):
             raise ValueError("The timeout must be greater than 0.")
         if isinstance(sequence_numbers, six.integer_types):
             sequence_numbers = [sequence_numbers]
-        if not sequence_numbers:
-            raise ValueError("At least one sequence number must be specified.")
+        if len(sequence_numbers) == 0:
+            return [] # no-op on empty list.
         self._open()
         try:
             receive_mode = self._receive_mode.value.value

sdk/servicebus/azure-servicebus/azure/servicebus/_servicebus_sender.py

@@ -259,6 +259,8 @@ def schedule_messages(self, messages, schedule_time_utc, **kwargs):
         if isinstance(messages, ServiceBusMessage):
             request_body = self._build_schedule_request(schedule_time_utc, messages)
         else:
+            if len(messages) == 0:
+                return [] # No-op on empty list.
             request_body = self._build_schedule_request(schedule_time_utc, *messages)
         return self._mgmt_request_response_with_retry(
             REQUEST_RESPONSE_SCHEDULE_MESSAGE_OPERATION,
@@ -296,6 +298,8 @@ def cancel_scheduled_messages(self, sequence_numbers, **kwargs):
             numbers = [types.AMQPLong(sequence_numbers)]
         else:
             numbers = [types.AMQPLong(s) for s in sequence_numbers]
+        if len(numbers) == 0:
+            return None # no-op on empty list.
         request_body = {MGMT_REQUEST_SEQUENCE_NUMBERS: types.AMQPArray(numbers)}
         return self._mgmt_request_response_with_retry(
             REQUEST_RESPONSE_CANCEL_SCHEDULED_MESSAGE_OPERATION,
@@ -347,7 +351,7 @@ def send_messages(self, message, **kwargs):
         except TypeError:  # Message was not a list or generator.
             pass
         if isinstance(message, ServiceBusMessageBatch) and len(message) == 0:  # pylint: disable=len-as-condition
-            raise ValueError("A ServiceBusMessageBatch or list of Message must have at least one Message")
+            return # Short circuit noop if an empty list or batch is provided.
         if not isinstance(message, ServiceBusMessageBatch) and not isinstance(message, ServiceBusMessage):
             raise TypeError(
                 "Can only send azure.servicebus.<ServiceBusMessageBatch,ServiceBusMessage> or "

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

@@ -557,8 +557,8 @@ async def receive_deferred_messages(
             raise ValueError("The timeout must be greater than 0.")
         if isinstance(sequence_numbers, six.integer_types):
             sequence_numbers = [sequence_numbers]
-        if not sequence_numbers:
-            raise ValueError("At least one sequence number must be specified.")
+        if len(sequence_numbers) == 0:
+            return [] # no-op on empty list.
         await self._open()
         try:
             receive_mode = self._receive_mode.value.value

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

@@ -204,6 +204,8 @@ async def schedule_messages(
         if isinstance(messages, ServiceBusMessage):
             request_body = self._build_schedule_request(schedule_time_utc, messages)
         else:
+            if len(messages) == 0:
+                return [] # No-op on empty list.
             request_body = self._build_schedule_request(schedule_time_utc, *messages)
         return await self._mgmt_request_response_with_retry(
             REQUEST_RESPONSE_SCHEDULE_MESSAGE_OPERATION,
@@ -240,6 +242,8 @@ async def cancel_scheduled_messages(self, sequence_numbers: Union[int, List[int]
             numbers = [types.AMQPLong(sequence_numbers)]
         else:
             numbers = [types.AMQPLong(s) for s in sequence_numbers]
+        if len(numbers) == 0:
+            return None # no-op on empty list.
         request_body = {MGMT_REQUEST_SEQUENCE_NUMBERS: types.AMQPArray(numbers)}
         return await self._mgmt_request_response_with_retry(
             REQUEST_RESPONSE_CANCEL_SCHEDULED_MESSAGE_OPERATION,
@@ -294,7 +298,7 @@ async def send_messages(
         except TypeError:  # Message was not a list or generator.
             pass
         if isinstance(message, ServiceBusMessageBatch) and len(message) == 0:  # pylint: disable=len-as-condition
-            raise ValueError("A ServiceBusMessageBatch or list of Message must have at least one Message")
+            return # Short circuit noop if an empty list or batch is provided.
         if not isinstance(message, ServiceBusMessageBatch) and not isinstance(message, ServiceBusMessage):
             raise TypeError(
                 "Can only send azure.servicebus.<ServiceBusMessageBatch,ServiceBusMessage>"

sdk/servicebus/azure-servicebus/tests/async_tests/test_queues_async.py

@@ -67,6 +67,13 @@ async def test_async_queue_by_queue_client_conn_str_receive_handler_peeklock(sel
                     message = ServiceBusMessage("Handler message no. {}".format(i))
                     await sender.send_messages(message, timeout=5)
 
+                # Test that noop empty send works properly.
+                await sender.send_messages([])
+                await sender.send_messages(ServiceBusMessageBatch())
+                assert len(await sender.schedule_messages([], utc_now())) == 0
+                await sender.cancel_scheduled_messages([])
+
+            # Then test expected failure modes.
             with pytest.raises(ValueError):
                 async with sender:
                     raise AssertionError("Should raise ValueError")
@@ -85,6 +92,7 @@ async def test_async_queue_by_queue_client_conn_str_receive_handler_peeklock(sel
 
             receiver = sb_client.get_queue_receiver(servicebus_queue.name, max_wait_time=5)
             async with receiver:
+                assert len(await receiver.receive_deferred_messages([])) == 0
                 with pytest.raises(ValueError):
                     await receiver.receive_messages(max_wait_time=0)
 

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

@@ -128,8 +128,15 @@ def test_queue_by_queue_client_conn_str_receive_handler_peeklock(self, servicebu
                 message.to = 'to'
                 message.reply_to = 'reply_to'
                 sender.send_messages(message)
+
+            # Test that noop empty send works properly.
+            sender.send_messages([])
+            sender.send_messages(ServiceBusMessageBatch())
+            assert len(sender.schedule_messages([], utc_now())) == 0
+            sender.cancel_scheduled_messages([])
             sender.close()
 
+            # Then test expected failure modes.
             with pytest.raises(ValueError):
                 with sender:
                     raise AssertionError("Should raise ValueError")
@@ -145,6 +152,7 @@ def test_queue_by_queue_client_conn_str_receive_handler_peeklock(self, servicebu
 
             receiver = sb_client.get_queue_receiver(servicebus_queue.name, max_wait_time=5)
 
+            assert len(receiver.receive_deferred_messages([])) == 0
             with pytest.raises(ValueError):
                 receiver.receive_messages(max_wait_time=0)