diff --git a/swh/journal/tests/test_inmemory.py b/swh/journal/tests/test_inmemory.py
--- a/swh/journal/tests/test_inmemory.py
+++ b/swh/journal/tests/test_inmemory.py
@@ -11,8 +11,10 @@
 from swh.model.tests.swh_model_data import TEST_OBJECTS
 
 
-def test_write_additions_with_test_objects():
-    writer = InMemoryJournalWriter(value_sanitizer=model_object_dict_sanitizer)
+def test_write_additions_anonymized():
+    writer = InMemoryJournalWriter(
+        value_sanitizer=model_object_dict_sanitizer, anonymize=True
+    )
     expected = []
     priv_expected = []
 
@@ -30,6 +32,20 @@
     assert set(expected) == set(writer.objects)
 
 
+def test_write_additions():
+    writer = InMemoryJournalWriter(value_sanitizer=model_object_dict_sanitizer)
+    expected = set()
+
+    for object_type, objects in TEST_OBJECTS.items():
+        writer.write_additions(object_type, objects)
+
+        for object in objects:
+            expected.add((object_type, object))
+
+    assert not set(writer.privileged_objects)
+    assert expected == set(writer.objects)
+
+
 def test_write_addition_errors_without_unique_key():
     writer = InMemoryJournalWriter(value_sanitizer=model_object_dict_sanitizer)
 
diff --git a/swh/journal/writer/inmemory.py b/swh/journal/writer/inmemory.py
--- a/swh/journal/writer/inmemory.py
+++ b/swh/journal/writer/inmemory.py
@@ -17,16 +17,21 @@
     privileged_objects: List[Tuple[str, ValueProtocol]]
 
     def __init__(
-        self, value_sanitizer: Callable[[str, Dict[str, Any]], Dict[str, Any]]
+        self,
+        value_sanitizer: Callable[[str, Dict[str, Any]], Dict[str, Any]],
+        anonymize: bool = False,
     ):
         # Share the list of objects across processes, for RemoteAPI tests.
         self.manager = Manager()
         self.objects = self.manager.list()
         self.privileged_objects = self.manager.list()
+        self.anonymize = anonymize
 
     def write_addition(self, object_type: str, object_: ValueProtocol) -> None:
         object_.unique_key()  # Check this does not error, to mimic the kafka writer
-        anon_object_ = object_.anonymize()
+        anon_object_ = None
+        if self.anonymize:
+            anon_object_ = object_.anonymize()
         if anon_object_ is not None:
             self.privileged_objects.append((object_type, object_))
             self.objects.append((object_type, anon_object_))