Add hierarchical mail servers and credentials

tests/test_mail_profile_helpers.py

@@ -13,6 +13,7 @@ from govoplan_mail.backend.mail_profiles import (
     _assert_campaign_inherits_profile_credentials,
     _campaign_mail_profile_reference_id,
     _apply_profile_transport_update,
+    campaign_mail_selection_from_json,
     campaign_profile_transport_revisions,
     create_mail_server_profile,
     _merge_policy,
@@ -496,14 +497,26 @@ class MailProfileTransportHelperTests(unittest.TestCase):
 
 
 class MailProfilePolicyHelperTests(unittest.TestCase):
-    def test_campaign_contract_accepts_only_mail_profile_reference(self):
+    def test_campaign_contract_accepts_only_mail_owned_references(self):
         self.assertEqual(
             _campaign_mail_profile_reference_id({"mail_profile_id": " profile-1 "}),
             "profile-1",
         )
         for legacy in ("smtp", "imap", "credentials", "inherit_smtp_credentials"):
-            with self.subTest(legacy=legacy), self.assertRaisesRegex(MailProfileError, "select a Mail profile"):
+            with self.subTest(legacy=legacy), self.assertRaisesRegex(MailProfileError, "select Mail resources"):
                 _campaign_mail_profile_reference_id({"mail_profile_id": "profile-1", legacy: {}})
+        self.assertEqual(
+            campaign_mail_selection_from_json(
+                {
+                    "server": {
+                        "mail_profile_id": "profile-1",
+                        "smtp_server_id": "smtp-1",
+                        "smtp_credential_id": "credential-1",
+                    }
+                }
+            )["smtp_credential_id"],
+            "credential-1",
+        )
 
     def test_campaign_delivery_fails_when_policy_requires_local_credentials(self):
         profile = SimpleNamespace(imap_config=None)
@@ -511,7 +524,7 @@ class MailProfilePolicyHelperTests(unittest.TestCase):
             smtp_credentials=EffectiveCredentialPolicy(inherit=False),
         )
 
-        with self.assertRaisesRegex(MailProfileError, "Store the credentials on a Mail profile"):
+        with self.assertRaisesRegex(MailProfileError, "explicit credential selection"):
             _assert_campaign_inherits_profile_credentials(profile, policy)
 
     def test_merge_policy_respects_locked_lower_level_limits(self):