Index: tests/conftest.py
===================================================================
--- tests/conftest.py	(revision 918474db90c90fe2d895d37cd593e4b02c111be8)
+++ tests/conftest.py	(revision 4459fa45c6e226fc7254ed4675d84fecb1436004)
@@ -3,5 +3,5 @@
 from pathlib import Path
 from datetime import datetime
-from flexoentity import Domain, FlexoSignature, DomainManager, EntityRegistry
+from flexoentity import Domain, FlexoSignature, DomainManager, EntityRegistry, CompositeBackend
 from flexoentity import get_signing_backend, CertificateReference
 
@@ -30,5 +30,5 @@
 @pytest.fixture
 def sample_domain_manager():
-    return DomainManager(EntityRegistry())
+    return DomainManager(CompositeBackend(Domain), EntityRegistry())
 
 # ─────────────────────────────────────────────────────────────
Index: tests/test_domain.py
===================================================================
--- tests/test_domain.py	(revision 918474db90c90fe2d895d37cd593e4b02c111be8)
+++ tests/test_domain.py	(revision 4459fa45c6e226fc7254ed4675d84fecb1436004)
@@ -20,5 +20,5 @@
     sample_domain_manager.add(sample_domain)
     # Manager must know it now
-    assert sample_domain_manager.get("PY_ARITHM") is sample_domain
+    assert sample_domain_manager.get_by_domain_id("PY_ARITHM") is sample_domain
 
 
@@ -38,7 +38,6 @@
 def test_lookup_by_oid(sample_domain, sample_domain_manager):
     sample_domain_manager.add(sample_domain)
-    found = sample_domain_manager.get(sample_domain.domain_id)
+    found = sample_domain_manager.get_by_domain_id(sample_domain.domain_id)
     assert found is sample_domain
-
 
 # ---------------------------------------------------------------