fix: go into blocked status when database relation is removed (#20)

src/charm.py

@@ -91,6 +91,7 @@ def __init__(self, *args):
         self._sdcore_management = SdcoreManagementProvides(self, SDCORE_MANAGEMENT_RELATION_NAME)
         self.framework.observe(self.on.webui_pebble_ready, self._on_webui_pebble_ready)
         self.framework.observe(self.on.database_relation_joined, self._on_webui_pebble_ready)
+        self.framework.observe(self.on.database_relation_broken, self._on_database_relation_broken)
         self.framework.observe(self._database.on.database_created, self._on_database_created)
         self.framework.observe(self._database.on.endpoints_changed, self._on_database_created)
         self.framework.observe(
@@ -165,6 +166,14 @@ def _publish_sdcore_management_url(self, event: EventBase):
             management_url=self._get_webui_endpoint_url(),
         )
 
+    def _on_database_relation_broken(self, event: EventBase) -> None:
+        """Event handler for database relation broken.
+
+        Args:
+            event: Juju event
+        """
+        self.unit.status = BlockedStatus("Waiting for database relation")
+
     def _write_config_file(self, content: str) -> None:
         """Writes configuration file based on provided content.
 

tests/integration/test_integration.py

@@ -73,6 +73,27 @@ async def test_relate_and_wait_for_active_status(
     )
 
 
+@pytest.mark.skip(
+    reason="Bug in MongoDB: https://github.com/canonical/mongodb-k8s-operator/issues/218"
+)
+@pytest.mark.abort_on_fail
+async def test_remove_database_and_wait_for_blocked_status(ops_test: OpsTest, build_and_deploy):
+    assert ops_test.model
+    await ops_test.model.remove_application(DATABASE_APP_NAME, block_until_done=True)
+    await ops_test.model.wait_for_idle(apps=[APP_NAME], status="blocked", timeout=60)
+
+
+@pytest.mark.skip(
+    reason="Bug in MongoDB: https://github.com/canonical/mongodb-k8s-operator/issues/218"
+)
+@pytest.mark.abort_on_fail
+async def test_restore_database_and_wait_for_active_status(ops_test: OpsTest, build_and_deploy):
+    assert ops_test.model
+    await _deploy_database(ops_test)
+    await ops_test.model.integrate(relation1=APP_NAME, relation2=DATABASE_APP_NAME)
+    await ops_test.model.wait_for_idle(apps=[APP_NAME], status="active", timeout=1000)
+
+
 @pytest.mark.abort_on_fail
 async def test_when_scale_app_beyond_1_then_only_one_unit_is_active(
     ops_test: OpsTest, build_and_deploy

tests/unit/test_charm.py

@@ -6,7 +6,7 @@
 from unittest.mock import Mock, patch
 
 from ops import testing
-from ops.model import ActiveStatus, WaitingStatus
+from ops.model import ActiveStatus, BlockedStatus, WaitingStatus
 
 from charm import WebuiOperatorCharm
 
@@ -38,7 +38,7 @@ def setUp(self):
         self.addCleanup(self.harness.cleanup)
         self.harness.begin()
 
-    def _database_is_available(self) -> str:
+    def _create_database_relation_and_populate_data(self) -> int:
         database_url = "http://6.6.6.6"
         database_username = "banana"
         database_password = "pizza"
@@ -55,7 +55,17 @@ def _database_is_available(self) -> str:
                 "uris": database_url,
             },
         )
-        return database_url
+        return database_relation_id
+
+    def test_given_database_relation_not_created_when_pebble_ready_then_status_is_blocked(
+        self,
+    ):
+        self.harness.set_can_connect(container="webui", val=True)
+        self.harness.container_pebble_ready("webui")
+        self.assertEqual(
+            self.harness.model.unit.status,
+            BlockedStatus("Waiting for database relation to be created"),
+        )
 
     @patch("ops.model.Container.push")
     @patch("ops.model.Container.exists")
@@ -105,7 +115,7 @@ def test_given_config_file_is_written_when_pebble_ready_then_pebble_plan_is_appl
     ):
         patch_exists.return_value = True
 
-        self._database_is_available()
+        self._create_database_relation_and_populate_data()
 
         self.harness.container_pebble_ready(container_name="webui")
 
@@ -136,19 +146,33 @@ def test_given_config_file_is_written_when_pebble_ready_then_status_is_active(
     ):
         patch_exists.return_value = True
 
-        self._database_is_available()
+        self._create_database_relation_and_populate_data()
 
         self.harness.container_pebble_ready("webui")
 
         self.assertEqual(self.harness.model.unit.status, ActiveStatus())
 
+    @patch("ops.model.Container.exists")
+    def test_given_webui_charm_in_active_state_when_database_relation_breaks_then_status_is_blocked(  # noqa: E501
+        self, patch_exists
+    ):
+        patch_exists.return_value = True
+        database_relation_id = self._create_database_relation_and_populate_data()
+        self.harness.container_pebble_ready("webui")
+
+        self.harness.remove_relation(database_relation_id)
+
+        self.assertEqual(
+            self.harness.model.unit.status, BlockedStatus("Waiting for database relation")
+        )
+
     @patch("ops.model.Container.exists")
     def test_given_config_file_is_not_written_when_pebble_ready_then_status_is_waiting(
         self, patch_exists
     ):
         patch_exists.return_value = False
 
-        self._database_is_available()
+        self._create_database_relation_and_populate_data()
 
         self.harness.container_pebble_ready("webui")