Add contact point resolution contract

tests/test_contact_point_contract.py

@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import unittest
+from datetime import UTC, datetime
+
+from govoplan_core.core.contact_points import (
+    CAPABILITY_ADDRESSES_CONTACT_POINT_RESOLUTION,
+    CONTACT_POINT_CONTRACT_VERSION,
+    ContactPointResolutionRequest,
+    contact_point_resolution_provider,
+)
+from govoplan_core.core.distribution_lists import DistributionSourceReference
+
+
+class _Registry:
+    def __init__(self, capability: object | None = None) -> None:
+        self._capability = capability
+
+    def has_capability(self, name: str) -> bool:
+        return (
+            name == CAPABILITY_ADDRESSES_CONTACT_POINT_RESOLUTION
+            and self._capability is not None
+        )
+
+    def capability(self, _name: str) -> object:
+        return self._capability
+
+
+class ContactPointContractTests(unittest.TestCase):
+    def test_request_is_provider_neutral_and_versioned(self) -> None:
+        request = ContactPointResolutionRequest(
+            tenant_id="tenant-1",
+            subject=DistributionSourceReference(
+                provider="idm",
+                resource_type="identity",
+                resource_id="identity-1",
+            ),
+            effective_at=datetime(2026, 8, 2, tzinfo=UTC),
+            requested_channels=("email", "postal"),
+            address_purpose="official",
+            fallback_rule="primary",
+            postal_format="international",
+        )
+
+        self.assertEqual("1.0", CONTACT_POINT_CONTRACT_VERSION)
+        self.assertEqual("idm", request.subject.provider)
+        self.assertEqual(("email", "postal"), request.requested_channels)
+
+    def test_accessor_rejects_objects_that_do_not_implement_the_protocol(self) -> None:
+        self.assertIsNone(contact_point_resolution_provider(None))
+        self.assertIsNone(contact_point_resolution_provider(_Registry(object())))
+
+
+if __name__ == "__main__":
+    unittest.main()