observe mongodb relation events

src/charm.py

@@ -246,6 +246,11 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
             self.on.update_dependencies_action, self._on_update_dependencies_action
         )
         self.framework.observe(self.on.update_status, self._on_update_status)
+        self.framework.observe(self.on.mongodb_relation_joined, self._on_mongodb_relation_joined)
+        self.framework.observe(
+            self.on.mongodb_relation_departed, self._on_mongodb_relation_departed
+        )
+        self.framework.observe(self.on.mongodb_relation_changed, self._on_mongodb_relation_changed)
 
     def _setup_state(self) -> CharmState:
         """Set up the charm state.
@@ -686,7 +691,26 @@ def _check_and_update_local_lxd_dependencies(
 
     @catch_charm_errors
     def _on_reconcile_runners(self, _: ReconcileRunnersEvent) -> None:
-        """Handle the reconciliation of runners."""
+        """Event handler for reconciling runners."""
+        self._trigger_reconciliation()
+
+    @catch_charm_errors
+    def _on_mongodb_relation_joined(self, _: ops.RelationEvent) -> None:
+        """Handle the MongoDB relation joined event."""
+        self._trigger_reconciliation()
+
+    @catch_charm_errors
+    def _on_mongodb_relation_changed(self, _: ops.RelationEvent) -> None:
+        """Handle the MongoDB relation changed event."""
+        self._trigger_reconciliation()
+
+    @catch_charm_errors
+    def _on_mongodb_relation_departed(self, _: ops.RelationEvent) -> None:
+        """Handle the departure of the MongoDB relation."""
+        self._trigger_reconciliation()
+
+    def _trigger_reconciliation(self) -> None:
+        """Trigger the reconciliation of runners."""
         self.unit.status = MaintenanceStatus("Reconciling runners")
         state = self._setup_state()
 

tests/unit/test_charm.py

@@ -417,6 +417,31 @@ def test_charm_goes_into_waiting_state_on_missing_integration_data(
     assert "mock error" in harness.charm.unit.status.message
 
 
+@pytest.mark.parametrize(
+    "hook",
+    [
+        pytest.param("mongodb_relation_joined", id="Relation Joined"),
+        pytest.param("mongodb_relation_changed", id="Relation Changed"),
+        pytest.param("mongodb_relation_departed", id="Relation Departed"),
+    ],
+)
+def test_mongodb_integration_events_trigger_reconciliation(
+    hook: str, monkeypatch: pytest.MonkeyPatch, harness: Harness
+):
+    """
+    arrange: Mock charm._trigger_reconciliation.
+    act: Fire mongodb relation events.
+    assert: _trigger_reconciliation has been called.
+    """
+    reconcliation_mock = MagicMock()
+    relation_mock = MagicMock()
+    relation_mock.name = "mongodb"
+    relation_mock.id = 0
+    monkeypatch.setattr("charm.GithubRunnerCharm._trigger_reconciliation", reconcliation_mock)
+    getattr(harness.charm.on, hook).emit(relation=relation_mock)
+    reconcliation_mock.assert_called_once()
+
+
 # New tests should not be added here. This should be refactored to pytest over time.
 # New test should be written with pytest, similar to the above tests.
 # Consider to rewrite test with pytest if the tests below needs to be changed.