test: add extra test for dyn batching

tests/integration/dynamic_batching/test_dynamic_batching.py

@@ -289,6 +289,45 @@ def test_timeout_no_use(add_parameters, use_stream, use_dynamic_batching):
                 assert time_taken < 2
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize('use_custom_metric', [False, True])
+@pytest.mark.parametrize('use_dynamic_batching', [False, True])
+async def test_timeout_no_use_custom(use_dynamic_batching, use_custom_metric):
+    class TextUseCustomDynBatch(Executor):
+        @requests(on='/foo')
+        @dynamic_batching(custom_metric=lambda d: len(d.text))
+        def fun(self, docs, **kwargs):
+            if use_custom_metric:
+                self.logger.debug(f'Received {len(docs)} in "/foo" call with with custom metric and sum of text lengths? {sum([len(d.text) for d in docs])}')
+            else:
+                self.logger.debug(
+                    f'Received {len(docs)} in "/foo" call with sum of text lengths? {sum([len(d.text) for d in docs])}')
+            time.sleep(1)
+            for doc in docs:
+                doc.text += FOO_SUCCESS_MSG
+
+    d = Deployment(uses=TextUseCustomDynBatch, uses_dynamic_batching={'/foo': {'timeout': 2000, "preferred_batch_size": 10, 'use_dynamic_batching': use_dynamic_batching, 'use_custom_metric': use_custom_metric}})
+    with d:
+        start_time = time.time()
+        inputs = DocumentArray([Document(text='ab') for _ in range(8)])
+        client = Client(port=d.port, asyncio=True, protocol=d.protocol)
+        async for _ in client.post('/foo', inputs=inputs, request_size=1):
+            pass
+        time_taken = time.time() - start_time
+        if not use_dynamic_batching:
+            # in this case it should simply call once for each
+            assert time_taken > 8, 'Timeout ended too fast'
+            assert time_taken < 8 + TIMEOUT_TOLERANCE, 'Timeout ended too slowly'
+        elif not use_custom_metric:
+            # in this case it should accumulate all in 2 seconds, and spend only 1 second inside call
+            assert time_taken > 3, 'Timeout ended too fast'
+            assert time_taken < 3 + TIMEOUT_TOLERANCE, 'Timeout ended too slowly'
+        elif use_custom_metric:
+            # in this case it should accumulate all before 2 seconds, and divide the call in 2 calls
+            assert time_taken > 2, 'Timeout ended too fast'
+            assert time_taken < 2 + TIMEOUT_TOLERANCE, 'Timeout ended too slowly'
+
+
 @pytest.mark.parametrize(
     'add_parameters',
     [