diff --git a/swh/loader/package/tests/test_loader.py b/swh/loader/package/tests/test_loader.py
index 28eb318..5d96ba4 100644
--- a/swh/loader/package/tests/test_loader.py
+++ b/swh/loader/package/tests/test_loader.py
@@ -1,136 +1,136 @@
 # Copyright (C) 2019-2021  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import hashlib
 import string
-from unittest.mock import MagicMock
+from unittest.mock import Mock
 
 import attr
 import pytest
 
 from swh.loader.package.loader import BasePackageInfo, PackageLoader
 
 
 class FakeStorage:
     def origin_add(self, origins):
         raise ValueError("We refuse to add an origin")
 
     def origin_visit_get_latest(self, origin):
         return None
 
 
 class FakeStorage2(FakeStorage):
     def origin_add(self, origins):
         pass
 
     def origin_visit_add(self, visits):
         raise ValueError("We refuse to add an origin visit")
 
 
 def test_loader_origin_visit_failure(swh_storage):
     """Failure to add origin or origin visit should failed immediately
 
     """
     loader = PackageLoader(swh_storage, "some-url")
     loader.storage = FakeStorage()
 
     actual_load_status = loader.load()
     assert actual_load_status == {"status": "failed"}
 
     loader.storage = FakeStorage2()
 
     actual_load_status2 = loader.load()
     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
     p_info.extid.assert_not_called()
     loader.known_artifact_to_extid.assert_not_called()
 
     p_info.extid.reset_mock()
 
     # Some artifacts, but the PackageInfo does not support extids
     p_info.extid.return_value = None
     assert loader.resolve_revision_from_artifacts(known_artifacts, p_info) is None
     p_info.extid.assert_called_once()
     loader.known_artifact_to_extid.assert_not_called()
 
     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"})
     loader.known_artifact_to_extid.assert_any_call({"key": "extid-of-bbbb"})
 
     p_info.extid.reset_mock()
     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"})
 
 
 def test_manifest_extid():
     """Compute primary key should return the right identity
 
     """
 
     @attr.s
     class TestPackageInfo(BasePackageInfo):
         a = attr.ib()
         b = attr.ib()
         length = attr.ib()
         filename = attr.ib()
         version = attr.ib()
 
         MANIFEST_FORMAT = string.Template("$a $b")
 
     p_info = TestPackageInfo(
         url="http://example.org/",
         a=1,
         b=2,
         length=221837,
         filename="8sync-0.1.0.tar.gz",
         version="0.1.0",
     )
 
     actual_id = p_info.extid()
     assert actual_id == ("package-manifest-sha256", hashlib.sha256(b"1 2").digest())
 
 
 def test_no_env_swh_config_filename_raise(monkeypatch):
     """No SWH_CONFIG_FILENAME environment variable makes package loader init raise
 
     """
 
     class DummyPackageLoader(PackageLoader):
         """A dummy package loader for test purpose"""
 
         pass
 
     monkeypatch.delenv("SWH_CONFIG_FILENAME", raising=False)
 
     with pytest.raises(
         AssertionError, match="SWH_CONFIG_FILENAME environment variable is undefined"
     ):
         DummyPackageLoader.from_configfile(url="some-url")