Fix allowed units relation data field (#172)

src/relations/db.py

@@ -360,7 +360,7 @@ def _comma_split(s) -> Iterable[str]:
 
     def _get_allowed_units(self, relation: Relation) -> str:
         """Build the list of allowed units as in the legacy charm."""
-        return ",".join(
+        return " ".join(
             sorted(
                 unit.name
                 for unit in relation.data

tests/integration/helpers.py

@@ -312,6 +312,7 @@ async def deploy_and_relate_bundle_with_postgresql(
     ops_test: OpsTest,
     bundle_name: str,
     main_application_name: str,
+    main_application_num_units: int = None,
     relation_name: str = "db",
     status: str = "active",
     status_message: str = None,
@@ -324,6 +325,8 @@ async def deploy_and_relate_bundle_with_postgresql(
         bundle_name: The name of the bundle to deploy.
         main_application_name: The name of the application that should be
             related to PostgreSQL.
+        main_application_num_units: Optional number of units for the main
+            application.
         relation_name: The name of the relation to use in PostgreSQL
             (db or db-admin).
         status: Status to wait for in the application after relating
@@ -343,6 +346,11 @@ async def deploy_and_relate_bundle_with_postgresql(
             bundle_yaml = archive.read("bundle.yaml")
             data = yaml.load(bundle_yaml, Loader=yaml.FullLoader)
 
+            if main_application_num_units is not None:
+                data["applications"][main_application_name][
+                    "num_units"
+                ] = main_application_num_units
+
             # Save the list of relations other than `db` and `db-admin`,
             # so we can add them back later.
             other_relations = [

tests/integration/test_db.py

@@ -328,10 +328,10 @@ async def test_canonical_livepatch_onprem_bundle_db(ops_test: OpsTest) -> None:
         ops_test,
         "canonical-livepatch-onprem",
         LIVEPATCH_APP_NAME,
-        "db",
-        "blocked",
-        "✘ sync_token not set",
-        overlay,
+        relation_name="db",
+        status="blocked",
+        status_message="✘ sync_token not set",
+        overlay=overlay,
     )
 
     action = await ops_test.model.units.get(f"{LIVEPATCH_APP_NAME}/0").run_action("schema-upgrade")

tests/integration/test_db_admin.py

@@ -43,7 +43,11 @@ async def test_landscape_scalable_bundle_db(ops_test: OpsTest, charm: str) -> No
 
     # Deploy and test the Landscape Scalable bundle (using this PostgreSQL charm).
     relation_id = await deploy_and_relate_bundle_with_postgresql(
-        ops_test, "ch:landscape-scalable", LANDSCAPE_APP_NAME, RELATION_NAME
+        ops_test,
+        "ch:landscape-scalable",
+        LANDSCAPE_APP_NAME,
+        main_application_num_units=2,
+        relation_name=RELATION_NAME,
     )
     await check_databases_creation(
         ops_test,

tests/unit/test_db.py

@@ -645,3 +645,15 @@ def test_update_endpoints_without_relation(
                     "standbys" in unit_relation_data
                     and standbys + user == unit_relation_data["standbys"]
                 )
+
+    def test_get_allowed_units(self):
+        # No allowed units from the current database application.
+        peer_relation = self.harness.model.get_relation(PEER, self.peer_rel_id)
+        self.assertEqual(self.legacy_db_relation._get_allowed_units(peer_relation), "")
+
+        # List of space separated allowed units from the other application.
+        self.harness.add_relation_unit(self.rel_id, "application/1")
+        db_relation = self.harness.model.get_relation(RELATION_NAME, self.rel_id)
+        self.assertEqual(
+            self.legacy_db_relation._get_allowed_units(db_relation), "application/0 application/1"
+        )