diff --git a/swh/provenance/tests/conftest.py b/swh/provenance/tests/conftest.py
--- a/swh/provenance/tests/conftest.py
+++ b/swh/provenance/tests/conftest.py
@@ -5,7 +5,7 @@
 
 from datetime import datetime, timedelta, timezone
 from os import path
-from typing import Any, Dict, Generator, Iterable
+from typing import Any, Dict, Generator, List
 
 from _pytest.fixtures import SubRequest
 import mongomock.database
@@ -15,12 +15,13 @@
 from pytest_postgresql.factories import postgresql
 
 from swh.journal.serializers import msgpack_ext_hook
+from swh.model.model import BaseModel
 from swh.provenance import get_provenance, get_provenance_storage
 from swh.provenance.archive import ArchiveInterface
 from swh.provenance.interface import ProvenanceInterface, ProvenanceStorageInterface
 from swh.provenance.storage.archive import ArchiveStorage
 from swh.storage.interface import StorageInterface
-from swh.storage.replay import OBJECT_CONVERTERS, process_replay_objects
+from swh.storage.replay import OBJECT_CONVERTERS, OBJECT_FIXERS, process_replay_objects
 
 
 @pytest.fixture(
@@ -100,12 +101,22 @@
     return ArchiveStorage(swh_storage)
 
 
+def fill_storage(storage: StorageInterface, data: Dict[str, List[dict]]) -> None:
+    objects = {
+        objtype: [objs_from_dict(objtype, d) for d in dicts]
+        for objtype, dicts in data.items()
+    }
+    process_replay_objects(objects, storage=storage)
+
+
 def get_datafile(fname: str) -> str:
     return path.join(path.dirname(__file__), "data", fname)
 
 
-def load_repo_data(repo: str) -> Dict[str, Any]:
-    data: Dict[str, Any] = {}
+# TODO: this should return Dict[str, List[BaseModel]] directly, but it requires
+#       refactoring several tests
+def load_repo_data(repo: str) -> Dict[str, List[dict]]:
+    data: Dict[str, List[dict]] = {}
     with open(get_datafile(f"{repo}.msgpack"), "rb") as fobj:
         unpacker = msgpack.Unpacker(
             fobj,
@@ -119,16 +130,11 @@
     return data
 
 
-def filter_dict(d: Dict[Any, Any], keys: Iterable[Any]) -> Dict[Any, Any]:
-    return {k: v for (k, v) in d.items() if k in keys}
-
-
-def fill_storage(storage: StorageInterface, data: Dict[str, Any]) -> None:
-    data = {
-        object_type: [OBJECT_CONVERTERS[object_type](d) for d in values]
-        for object_type, values in data.items()
-    }
-    process_replay_objects(data, storage=storage)
+def objs_from_dict(object_type: str, dict_repr: dict) -> BaseModel:
+    if object_type in OBJECT_FIXERS:
+        dict_repr = OBJECT_FIXERS[object_type](dict_repr)
+    obj = OBJECT_CONVERTERS[object_type](dict_repr)
+    return obj
 
 
 # TODO: remove this function in favour of TimestampWithTimezone.to_datetime