diff --git a/swh/journal/pytest_plugin.py b/swh/journal/pytest_plugin.py
--- a/swh/journal/pytest_plugin.py
+++ b/swh/journal/pytest_plugin.py
@@ -6,7 +6,7 @@
 from collections import defaultdict
 import random
 import string
-from typing import Collection, Dict, Iterator, Optional
+from typing import Any, Collection, Dict, Iterator, Optional
 
 import attr
 from confluent_kafka import Consumer, KafkaException, Producer
@@ -17,6 +17,25 @@
 from swh.journal.tests.journal_data import TEST_OBJECTS
 
 
+def ensure_lists(value: Any) -> Any:
+    """
+    >>> ensure_lists(["foo", 42])
+    ['foo', 42]
+    >>> ensure_lists(("foo", 42))
+    ['foo', 42]
+    >>> ensure_lists({"a": ["foo", 42]})
+    {'a': ['foo', 42]}
+    >>> ensure_lists({"a": ("foo", 42)})
+    {'a': ['foo', 42]}
+    """
+    if isinstance(value, (tuple, list)):
+        return list(map(ensure_lists, value))
+    elif isinstance(value, dict):
+        return dict(ensure_lists(list(value.items())))
+    else:
+        return value
+
+
 def consume_messages(consumer, kafka_prefix, expected_messages):
     """Consume expected_messages from the consumer;
     Sort them all into a consumed_objects dict"""
@@ -95,7 +114,7 @@
             expected_value = value.to_dict()
             if value.object_type in ("content", "skipped_content"):
                 expected_value.pop("ctime", None)
-            assert expected_value in received_values, (
+            assert ensure_lists(expected_value) in received_values, (
                 f"expected {object_type} value {value!r} is "
                 "absent from consumed messages"
             )
diff --git a/swh/journal/serializers.py b/swh/journal/serializers.py
--- a/swh/journal/serializers.py
+++ b/swh/journal/serializers.py
@@ -103,7 +103,7 @@
 
 def kafka_to_value(kafka_value: bytes) -> Any:
     """Deserialize some data stored in kafka"""
-    value = msgpack.unpackb(
+    return msgpack.unpackb(
         kafka_value,
         raw=False,
         object_hook=decode_types_bw,
@@ -111,13 +111,3 @@
         strict_map_key=False,
         timestamp=3,  # convert Timestamp in datetime objects (tz UTC)
     )
-    return ensure_tuples(value)
-
-
-def ensure_tuples(value: Any) -> Any:
-    if isinstance(value, (tuple, list)):
-        return tuple(map(ensure_tuples, value))
-    elif isinstance(value, dict):
-        return dict(ensure_tuples(list(value.items())))
-    else:
-        return value
diff --git a/swh/journal/tests/test_client.py b/swh/journal/tests/test_client.py
--- a/swh/journal/tests/test_client.py
+++ b/swh/journal/tests/test_client.py
@@ -34,7 +34,7 @@
     ),
     "synthetic": False,
     "metadata": None,
-    "parents": (),
+    "parents": [],
     "id": b"\x8b\xeb\xd1\x9d\x07\xe2\x1e0\xe2 \x91X\x8d\xbd\x1c\xa8\x86\xdeB\x0c",
 }