diff --git a/swh/model/hypothesis_strategies.py b/swh/model/hypothesis_strategies.py
--- a/swh/model/hypothesis_strategies.py
+++ b/swh/model/hypothesis_strategies.py
@@ -380,31 +380,45 @@
     ).map(Snapshot.from_dict)
 
 
-def objects():
-    return one_of(
-        origins().map(lambda x: ("origin", x)),
-        origin_visits().map(lambda x: ("origin_visit", x)),
-        origin_visit_statuses().map(lambda x: ("origin_visit_status", x)),
-        snapshots().map(lambda x: ("snapshot", x)),
-        releases().map(lambda x: ("release", x)),
-        revisions().map(lambda x: ("revision", x)),
-        directories().map(lambda x: ("directory", x)),
-        contents().map(lambda x: ("content", x)),
-    )
+def objects(blacklist_types=()):
+    """generates a random couple (type, obj)
 
+    which obj is an instance of the Model class corresponding to obj_type.
+    """
+    args = [
+        obj_gen().map(lambda x, obj_type=obj_type: (obj_type, x))
+        for (obj_type, obj_gen) in (
+            ("origin", origins),
+            ("origin_visit", origin_visits),
+            ("origin_visit_status", origin_visit_statuses),
+            ("snapshot", snapshots),
+            ("release", releases),
+            ("revision", revisions),
+            ("directory", directories),
+            ("content", contents),
+        )
+        if obj_type not in blacklist_types
+    ]
+    return one_of(*args)
 
-def object_dicts():
+
+def object_dicts(blacklist_types=()):
     """generates a random couple (type, dict)
 
     which dict is suitable for <ModelForType>.from_dict() factory methods.
     """
-    return one_of(
-        origins_d().map(lambda x: ("origin", x)),
-        origin_visits_d().map(lambda x: ("origin_visit", x)),
-        origin_visit_statuses_d().map(lambda x: ("origin_visit_status", x)),
-        snapshots_d().map(lambda x: ("snapshot", x)),
-        releases_d().map(lambda x: ("release", x)),
-        revisions_d().map(lambda x: ("revision", x)),
-        directories_d().map(lambda x: ("directory", x)),
-        contents_d().map(lambda x: ("content", x)),
-    )
+    args = [
+        obj_gen().map(lambda x, obj_type=obj_type: (obj_type, x))
+        for (obj_type, obj_gen) in [
+            ("origin", origins_d),
+            ("origin_visit", origin_visits_d),
+            ("origin_visit_status", origin_visit_statuses_d),
+            ("snapshot", snapshots_d),
+            ("release", releases_d),
+            ("revision", revisions_d),
+            ("directory", directories_d),
+            ("content", contents_d),
+        ]
+        if obj_type not in blacklist_types
+    ]
+    return one_of(*args)
diff --git a/swh/model/tests/test_hypothesis_strategies.py b/swh/model/tests/test_hypothesis_strategies.py
--- a/swh/model/tests/test_hypothesis_strategies.py
+++ b/swh/model/tests/test_hypothesis_strategies.py
@@ -22,6 +22,11 @@
     attr.validate(object_)
 
 
+@given(object_dicts(blacklist_types=("origin_visit", "directory")))
+def test_generation_blacklist(obj_type_and_obj):
+    assert obj_type_and_obj[0] not in ("origin_visit", "directory")
+
+
 def assert_nested_dict(obj):
     """Tests the object is a nested dict and contains no more class
     from swh.model.model."""
@@ -59,6 +64,11 @@
             assert branch is None or branch["target_type"] in target_types
 
 
+@given(object_dicts(blacklist_types=("release", "content")))
+def test_dicts_generation_blacklist(obj_type_and_obj):
+    assert obj_type_and_obj[0] not in ("release", "content")
+
+
 @given(objects())
 def test_model_to_dicts(obj_type_and_obj):
     (obj_type, object_) = obj_type_and_obj