diff --git a/kallithea/tests/__init__.py b/kallithea/tests/__init__.py
--- a/kallithea/tests/__init__.py
+++ b/kallithea/tests/__init__.py
@@ -22,5 +22,7 @@ import pytest
 
 if getattr(pytest, 'register_assert_rewrite', None):
     # make sure that all asserts under kallithea/tests benefit from advanced
-    # assert reporting with pytest-3.0.0+.
-    pytest.register_assert_rewrite('kallithea.tests.')
+    # assert reporting with pytest-3.0.0+, including api/api_base.py,
+    # models/common.py etc.
+    # See also: https://docs.pytest.org/en/latest/assert.html#advanced-assertion-introspection
+    pytest.register_assert_rewrite('kallithea.tests')