diff --git a/swh/loader/package/tests/test_loader.py b/swh/loader/package/tests/test_loader.py
--- a/swh/loader/package/tests/test_loader.py
+++ b/swh/loader/package/tests/test_loader.py
@@ -5,7 +5,7 @@
 
 import hashlib
 import string
-from unittest.mock import MagicMock
+from unittest.mock import Mock
 
 import attr
 import pytest
@@ -45,18 +45,18 @@
     assert actual_load_status2 == {"status": "failed"}
 
 
-def test_resolve_revision_from_artifacts():
-    loader = PackageLoader(None, None)
-    loader.known_artifact_to_extid = MagicMock(
-        wraps=lambda known_artifact: known_artifact["key"].encode()
+def test_resolve_revision_from_artifacts() -> None:
+    loader = PackageLoader(None, None)  # type: ignore
+    loader.known_artifact_to_extid = Mock(  # type: ignore
+        wraps=lambda known_artifact: ("extid-type", known_artifact["key"].encode())
     )
 
     known_artifacts = {
-        b"a" * 40: {"key": "extid-of-aaaa"},
-        b"b" * 40: {"key": "extid-of-bbbb"},
+        b"a" * 20: {"key": "extid-of-aaaa"},
+        b"b" * 20: {"key": "extid-of-bbbb"},
     }
 
-    p_info = MagicMock()
+    p_info = Mock(wraps=BasePackageInfo(None, None))  # type: ignore
 
     # No known artifact -> it would be useless to compute the extid
     assert loader.resolve_revision_from_artifacts({}, p_info) is None
@@ -74,7 +74,7 @@
     p_info.extid.reset_mock()
 
     # Some artifacts, and the PackageInfo is not one of them (ie. cache miss)
-    p_info.extid.return_value = b"extid-of-cccc"
+    p_info.extid.return_value = ("extid-type", b"extid-of-cccc")
     assert loader.resolve_revision_from_artifacts(known_artifacts, p_info) is None
     p_info.extid.assert_called_once()
     loader.known_artifact_to_extid.assert_any_call({"key": "extid-of-aaaa"})
@@ -84,8 +84,8 @@
     loader.known_artifact_to_extid.reset_mock()
 
     # Some artifacts, and the PackageInfo is one of them (ie. cache hit)
-    p_info.extid.return_value = b"extid-of-aaaa"
-    assert loader.resolve_revision_from_artifacts(known_artifacts, p_info) == b"a" * 40
+    p_info.extid.return_value = ("extid-type", b"extid-of-aaaa")
+    assert loader.resolve_revision_from_artifacts(known_artifacts, p_info) == b"a" * 20
     p_info.extid.assert_called_once()
     loader.known_artifact_to_extid.assert_called_once_with({"key": "extid-of-aaaa"})