feat: add support for ActionEvent.id

scenario/runtime.py

@@ -180,25 +180,26 @@ def _cleanup_env(env):
 
     def _get_event_env(self, state: "State", event: "Event", charm_root: Path):
         """Build the simulated environment the operator framework expects."""
-        if event.name.endswith("_action"):
-            # todo: do we need some special metadata, or can we assume action names
-            #  are always dashes?
-            action_name = event.name[: -len("_action")].replace("_", "-")
-        else:
-            action_name = ""
-
         env = {
             "JUJU_VERSION": self._juju_version,
             "JUJU_UNIT_NAME": f"{self._app_name}/{self._unit_id}",
             "_": "./dispatch",
             "JUJU_DISPATCH_PATH": f"hooks/{event.name}",
             "JUJU_MODEL_NAME": state.model.name,
-            "JUJU_ACTION_NAME": action_name,
             "JUJU_MODEL_UUID": state.model.uuid,
             "JUJU_CHARM_DIR": str(charm_root.absolute()),
             # todo consider setting pwd, (python)path
         }
 
+        if event._is_action_event and (action := event.action):
+            env.update(
+                {
+                    # TODO: we should check we're doing the right thing here.
+                    "JUJU_ACTION_NAME": action.name.replace("_", "-"),
+                    "JUJU_ACTION_UUID": action.id,
+                },
+            )
+
         if event._is_relation_event and (relation := event.relation):
             if isinstance(relation, PeerRelation):
                 remote_app_name = self._app_name

scenario/sequences.py

@@ -58,9 +58,11 @@ def generate_startup_sequence(state_template: State):
         (
             (
                 Event(
-                    "leader_elected"
-                    if state_template.leader
-                    else "leader_settings_changed",
+                    (
+                        "leader_elected"
+                        if state_template.leader
+                        else "leader_settings_changed"
+                    ),
                 ),
                 state_template.copy(),
             ),

scenario/state.py

@@ -1423,12 +1423,31 @@ def deferred(self, handler: Callable, event_id: int = 1) -> DeferredEvent:
         )
 
 
+_next_action_id_counter = 1
+
+
+def next_action_id(update=True):
+    global _next_action_id_counter
+    cur = _next_action_id_counter
+    if update:
+        _next_action_id_counter += 1
+    # Juju currently uses numbers for the ID, but in the past used UUIDs, so
+    # we need these to be strings.
+    return str(cur)
+
+
 @dataclasses.dataclass(frozen=True)
 class Action(_DCBase):
     name: str
 
     params: Dict[str, "AnyJson"] = dataclasses.field(default_factory=dict)
 
+    id: str = dataclasses.field(default_factory=next_action_id)
+    """Juju action ID.
+
+    Every action invocation is automatically assigned a new one. Override in
+    the rare cases where a specific ID is required."""
+
     @property
     def event(self) -> Event:
         """Helper to generate an action event from this action."""

tests/test_context.py

@@ -4,6 +4,7 @@
 from ops import CharmBase
 
 from scenario import Action, Context, Event, State
+from scenario.state import next_action_id
 
 
 class MyCharm(CharmBase):
@@ -31,6 +32,7 @@ def test_run():
 def test_run_action():
     ctx = Context(MyCharm, meta={"name": "foo"})
     state = State()
+    expected_id = next_action_id(update=False)
 
     with patch.object(ctx, "_run_action") as p:
         ctx._output_state = (
@@ -46,6 +48,7 @@ def test_run_action():
     assert isinstance(a, Action)
     assert a.event.name == "do_foo_action"
     assert s is state
+    assert a.id == expected_id
 
 
 def test_clear():

tests/test_e2e/test_actions.py

@@ -1,4 +1,5 @@
 import pytest
+from ops import __version__ as ops_version
 from ops.charm import ActionEvent, CharmBase
 from ops.framework import Framework
 
@@ -135,3 +136,46 @@ def handle_evt(charm: CharmBase, evt: ActionEvent):
     assert out.failure == "failed becozz"
     assert out.logs == ["log1", "log2"]
     assert out.success is False
+
+
+def _ops_less_than(wanted_major, wanted_minor):
+    major, minor = (int(v) for v in ops_version.split(".")[:2])
+    if major < wanted_major:
+        return True
+    if major == wanted_major and minor < wanted_minor:
+        return True
+    return False
+
+
+@pytest.mark.skipif(
+    _ops_less_than(2, 11), reason="ops 2.10 and earlier don't have ActionEvent.id"
+)
+def test_action_event_has_id(mycharm):
+    def handle_evt(charm: CharmBase, evt: ActionEvent):
+        if not isinstance(evt, ActionEvent):
+            return
+        assert isinstance(evt.id, str) and evt.id != ""
+
+    mycharm._evt_handler = handle_evt
+
+    action = Action("foo")
+    ctx = Context(mycharm, meta={"name": "foo"}, actions={"foo": {}})
+    ctx.run_action(action, State())
+
+
+@pytest.mark.skipif(
+    _ops_less_than(2, 11), reason="ops 2.10 and earlier don't have ActionEvent.id"
+)
+def test_action_event_has_override_id(mycharm):
+    uuid = "0ddba11-cafe-ba1d-5a1e-dec0debad"
+
+    def handle_evt(charm: CharmBase, evt: ActionEvent):
+        if not isinstance(evt, ActionEvent):
+            return
+        assert evt.id == uuid
+
+    mycharm._evt_handler = handle_evt
+
+    action = Action("foo", id=uuid)
+    ctx = Context(mycharm, meta={"name": "foo"}, actions={"foo": {}})
+    ctx.run_action(action, State())