consistency checks

scenario/consistency_checker.py

@@ -123,6 +123,9 @@ def check_event_consistency(
     if event._is_action_event:
         _check_action_event(charm_spec, event, errors, warnings)
 
+    if event._is_storage_event:
+        _check_storage_event(charm_spec, event, errors, warnings)
+
     return Results(errors, warnings)
 
 
@@ -190,6 +193,30 @@ def _check_action_event(
     _check_action_param_types(charm_spec, action, errors, warnings)
 
 
+def _check_storage_event(
+    charm_spec: _CharmSpec,
+    event: "Event",
+    errors: List[str],
+    warnings: List[str],  # noqa: U100
+):
+    storage = event.storage
+    if not storage:
+        errors.append(
+            "cannot construct a storage event without the Storage instance. "
+            "Please pass one.",
+        )
+    elif not event.name.startswith(normalize_name(storage.name)):
+        errors.append(
+            f"storage event should start with storage name. {event.name} does "
+            f"not start with {storage.name}.",
+        )
+    elif storage.name not in charm_spec.meta["storage"]:
+        errors.append(
+            f"storage event {event.name} refers to storage {storage.name} "
+            f"which is not declared in the charm metadata (metadata.yaml) under 'storage'.",
+        )
+
+
 def _check_action_param_types(
     charm_spec: _CharmSpec,
     action: Action,

tests/test_consistency_checker.py

@@ -12,6 +12,7 @@
     Relation,
     Secret,
     State,
+    Storage,
     SubordinateRelation,
     _CharmSpec,
 )
@@ -342,7 +343,7 @@ def test_relation_without_endpoint():
             relations=[Relation("foo", relation_id=1), Relation("bar", relation_id=1)]
         ),
         Event("start"),
-        _CharmSpec(MyCharm, meta={}),
+        _CharmSpec(MyCharm, meta={"name": "charlemagne"}),
     )
 
     assert_consistent(
@@ -357,3 +358,27 @@ def test_relation_without_endpoint():
             },
         ),
     )
+
+
+def test_storage_event():
+    storage = Storage("foo")
+    assert_inconsistent(
+        State(storage=[storage]),
+        Event("foo-storage-attached"),
+        _CharmSpec(MyCharm, meta={"name": "rupert"}),
+    )
+    assert_inconsistent(
+        State(storage=[storage]),
+        Event("foo-storage-attached"),
+        _CharmSpec(
+            MyCharm, meta={"name": "rupert", "storage": {"foo": {"type": "filesystem"}}}
+        ),
+    )
+
+    assert_consistent(
+        State(storage=[storage]),
+        storage.attached_event,
+        _CharmSpec(
+            MyCharm, meta={"name": "rupert", "storage": {"foo": {"type": "filesystem"}}}
+        ),
+    )