PoC for Context as the context manager.

scenario/context.py

@@ -154,11 +154,10 @@ def _get_output(self):
 
 
 class _ActionManager(_Manager):
-    if TYPE_CHECKING:  # pragma: no cover
-        output: ActionOutput  # pyright: ignore[reportIncompatibleVariableOverride]
+    output: ActionOutput  # pyright: ignore[reportIncompatibleVariableOverride]
 
-        def run(self) -> "ActionOutput":
-            return cast("ActionOutput", super().run())
+    def run_action(self) -> "ActionOutput":
+        return cast("ActionOutput", super().run())
 
     @property
     def _runner(self):
@@ -600,38 +599,30 @@ def _record_status(self, state: "State", is_app: bool):
         else:
             self.unit_status_history.append(state.unit_status)
 
-    def manager(self, event: "_Event", state: "State"):
+    def __call__(self, event: Union["_Event", "Action"], state: "State"):
         """Context manager to introspect live charm object before and after the event is emitted.
 
         Usage::
 
             ctx = Context(MyCharm)
-            with ctx.manager(ctx.on.start(), State()) as manager:
-                assert manager.charm._some_private_attribute == "foo"  # noqa
-                manager.run()  # this will fire the event
-                assert manager.charm._some_private_attribute == "bar"  # noqa
+            with ctx(ctx.on.start(), State()) as event:
+                event.charm._some_private_setup()
+                event.run()  # this will fire the event
+                assert event.charm._some_private_attribute == "bar"  # noqa
+
+            with ctx(Action("foo"), State()) as event:
+                event.charm._some_private_setup()
+                event.run_action()  # this will fire the event
+                assert event.charm._some_private_attribute == "bar"  # noqa
 
         Args:
-            event: the :class:`Event` that the charm will respond to.
+            event: the :class:`Event` or :class:`Action` that the charm will respond to.
             state: the :class:`State` instance to use when handling the Event.
         """
+        if isinstance(event, Action) or event.action:
+            return _ActionManager(self, event, state)
         return _EventManager(self, event, state)
 
-    def action_manager(self, action: "_Action", state: "State"):
-        """Context manager to introspect live charm object before and after the event is emitted.
-
-        Usage:
-        >>> with Context().action_manager(Action("foo"), State()) as manager:
-        >>>     assert manager.charm._some_private_attribute == "foo"  # noqa
-        >>>     manager.run()  # this will fire the event
-        >>>     assert manager.charm._some_private_attribute == "bar"  # noqa
-
-        :arg action: the Action that the charm will execute.
-        :arg state: the State instance to use as data source for the hook tool calls that the
-            charm will invoke when handling the Action (event).
-        """
-        return _ActionManager(self, action, state)
-
     @contextmanager
     def _run_event(self, event: "_Event", state: "State"):
         with self._run(event=event, state=state) as ops:

tests/helpers.py

@@ -58,12 +58,12 @@ def trigger(
             event = getattr(ctx.on, event)(tuple(state.containers)[0])
         else:
             event = getattr(ctx.on, event)()
-    with ctx.manager(event, state=state) as mgr:
+    with ctx(event, state=state) as event:
         if pre_event:
-            pre_event(mgr.charm)
-        state_out = mgr.run()
+            pre_event(event.charm)
+        state_out = event.run()
         if post_event:
-            post_event(mgr.charm)
+            post_event(event.charm)
     return state_out
 
 

tests/test_charm_spec_autoload.py

@@ -162,6 +162,6 @@ def test_config_defaults(tmp_path, legacy):
     ) as charm:
         # this would fail if there were no 'cuddles' relation defined in meta
         ctx = Context(charm)
-        with ctx.manager(ctx.on.start(), State()) as mgr:
-            mgr.run()
-            assert mgr.charm.config["foo"] is True
+        with ctx(ctx.on.start(), State()) as event:
+            event.run()
+            assert event.charm.config["foo"] is True

tests/test_context.py

@@ -53,9 +53,21 @@ def test_run_action():
 @pytest.mark.parametrize("unit_id", (1, 2, 42))
 def test_app_name(app_name, unit_id):
     ctx = Context(MyCharm, meta={"name": "foo"}, app_name=app_name, unit_id=unit_id)
-    with ctx.manager(ctx.on.start(), State()) as mgr:
-        assert mgr.charm.app.name == app_name
-        assert mgr.charm.unit.name == f"{app_name}/{unit_id}"
+    with ctx(ctx.on.start(), State()) as event:
+        assert event.charm.app.name == app_name
+        assert event.charm.unit.name == f"{app_name}/{unit_id}"
+
+
+def test_context_manager():
+    ctx = Context(MyCharm, meta={"name": "foo"}, actions={"act": {}})
+    state = State()
+    with ctx(ctx.on.start(), state) as event:
+        event.run()
+        assert event.charm.meta.name == "foo"
+
+    with ctx(Action("act"), state) as event:
+        event.run_action()
+        assert event.charm.meta.name == "foo"
 
 
 def test_action_output_no_positional_arguments():

tests/test_context_on.py

@@ -64,7 +64,7 @@ def test_simple_events(event_name, event_kind):
     ctx = scenario.Context(ContextCharm, meta=META, actions=ACTIONS)
     # These look like:
     #   ctx.run(ctx.on.install(), state)
-    with ctx.manager(getattr(ctx.on, event_name)(), scenario.State()) as mgr:
+    with ctx(getattr(ctx.on, event_name)(), scenario.State()) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -95,7 +95,7 @@ def test_simple_secret_events(as_kwarg, event_name, event_kind, owner):
     else:
         args = (secret,)
         kwargs = {}
-    with ctx.manager(getattr(ctx.on, event_name)(*args, **kwargs), state_in) as mgr:
+    with ctx(getattr(ctx.on, event_name)(*args, **kwargs), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -123,7 +123,7 @@ def test_revision_secret_events(event_name, event_kind):
     #   ctx.run(ctx.on.secret_expired(secret=secret, revision=revision), state)
     # The secret and revision must always be passed because the same event name
     # is used for all secrets.
-    with ctx.manager(getattr(ctx.on, event_name)(secret, revision=42), state_in) as mgr:
+    with ctx(getattr(ctx.on, event_name)(secret, revision=42), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -159,7 +159,7 @@ def test_storage_events(event_name, event_kind):
     state_in = scenario.State(storages=[storage])
     # These look like:
     #   ctx.run(ctx.on.storage_attached(storage), state)
-    with ctx.manager(getattr(ctx.on, event_name)(storage), state_in) as mgr:
+    with ctx(getattr(ctx.on, event_name)(storage), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -173,8 +173,8 @@ def test_action_event_no_params():
     ctx = scenario.Context(ContextCharm, meta=META, actions=ACTIONS)
     # These look like:
     #   ctx.run_action(ctx.on.action(action), state)
-    with ctx.action_manager(ctx.on.action("act"), scenario.State()) as mgr:
-        mgr.run()
+    with ctx(ctx.on.action("act"), scenario.State()) as mgr:
+        mgr.run_action()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
         event = mgr.charm.observed[0]
@@ -187,8 +187,8 @@ def test_action_event_with_params():
     #   ctx.run_action(ctx.on.action(action=action), state)
     # So that any parameters can be included and the ID can be customised.
     call_event = ctx.on.action("act", params={"param": "hello"})
-    with ctx.action_manager(call_event, scenario.State()) as mgr:
-        mgr.run()
+    with ctx(call_event, scenario.State()) as mgr:
+        mgr.run_action()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
         event = mgr.charm.observed[0]
@@ -203,7 +203,7 @@ def test_pebble_ready_event():
     state_in = scenario.State(containers=[container])
     # These look like:
     #   ctx.run(ctx.on.pebble_ready(container), state)
-    with ctx.manager(ctx.on.pebble_ready(container), state_in) as mgr:
+    with ctx(ctx.on.pebble_ready(container), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -232,7 +232,7 @@ def test_relation_app_events(as_kwarg, event_name, event_kind):
     else:
         args = (relation,)
         kwargs = {}
-    with ctx.manager(getattr(ctx.on, event_name)(*args, **kwargs), state_in) as mgr:
+    with ctx(getattr(ctx.on, event_name)(*args, **kwargs), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -249,7 +249,7 @@ def test_relation_complex_name():
     ctx = scenario.Context(ContextCharm, meta=meta, actions=ACTIONS)
     relation = scenario.Relation("foo-bar-baz")
     state_in = scenario.State(relations=[relation])
-    with ctx.manager(ctx.on.relation_created(relation), state_in) as mgr:
+    with ctx(ctx.on.relation_created(relation), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         event = mgr.charm.observed[0]
@@ -282,7 +282,7 @@ def test_relation_unit_events_default_unit(event_name, event_kind):
     # These look like:
     #   ctx.run(ctx.on.baz_relation_changed, state)
     # The unit is chosen automatically.
-    with ctx.manager(getattr(ctx.on, event_name)(relation), state_in) as mgr:
+    with ctx(getattr(ctx.on, event_name)(relation), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -308,9 +308,7 @@ def test_relation_unit_events(event_name, event_kind):
     state_in = scenario.State(relations=[relation])
     # These look like:
     #   ctx.run(ctx.on.baz_relation_changed(unit=unit_ordinal), state)
-    with ctx.manager(
-        getattr(ctx.on, event_name)(relation, remote_unit=2), state_in
-    ) as mgr:
+    with ctx(getattr(ctx.on, event_name)(relation, remote_unit=2), state_in) as mgr:
         mgr.run()
         assert len(mgr.charm.observed) == 2
         assert isinstance(mgr.charm.observed[1], ops.CollectStatusEvent)
@@ -327,7 +325,7 @@ def test_relation_departed_event():
     state_in = scenario.State(relations=[relation])
     # These look like:
     #   ctx.run(ctx.on.baz_relation_departed(unit=unit_ordinal, departing_unit=unit_ordinal), state)
-    with ctx.manager(
+    with ctx(
         ctx.on.relation_departed(relation, remote_unit=2, departing_unit=1), state_in
     ) as mgr:
         mgr.run()

tests/test_e2e/test_cloud_spec.py

@@ -47,14 +47,14 @@ def test_get_cloud_spec():
             name="lxd-model", type="lxd", cloud_spec=scenario_cloud_spec
         ),
     )
-    with ctx.manager(ctx.on.start(), state=state) as mgr:
+    with ctx(ctx.on.start(), state=state) as mgr:
         assert mgr.charm.model.get_cloud_spec() == expected_cloud_spec
 
 
 def test_get_cloud_spec_error():
     ctx = scenario.Context(MyCharm, meta={"name": "foo"})
     state = scenario.State(model=scenario.Model(name="lxd-model", type="lxd"))
-    with ctx.manager(ctx.on.start(), state) as mgr:
+    with ctx(ctx.on.start(), state) as mgr:
         with pytest.raises(ops.ModelError):
             mgr.charm.model.get_cloud_spec()
 
@@ -65,6 +65,6 @@ def test_get_cloud_spec_untrusted():
     state = scenario.State(
         model=scenario.Model(name="lxd-model", type="lxd", cloud_spec=cloud_spec),
     )
-    with ctx.manager(ctx.on.start(), state) as mgr:
+    with ctx(ctx.on.start(), state) as mgr:
         with pytest.raises(ops.ModelError):
             mgr.charm.model.get_cloud_spec()

tests/test_e2e/test_manager.py

@@ -65,15 +65,15 @@ def test_manager_reemit_fails(mycharm):
 
 def test_context_manager(mycharm):
     ctx = Context(mycharm, meta=mycharm.META)
-    with ctx.manager(ctx.on.start(), State()) as manager:
+    with ctx(ctx.on.start(), State()) as manager:
         state_out = manager.run()
         assert isinstance(state_out, State)
     assert ctx.emitted_events[0].handle.kind == "start"
 
 
 def test_context_action_manager(mycharm):
     ctx = Context(mycharm, meta=mycharm.META, actions=mycharm.ACTIONS)
-    with ctx.action_manager(ctx.on.action("do-x"), State()) as manager:
-        ao = manager.run()
+    with ctx(ctx.on.action("do-x"), State()) as manager:
+        ao = manager.run_action()
         assert isinstance(ao, ActionOutput)
     assert ctx.emitted_events[0].handle.kind == "do_x_action"

tests/test_e2e/test_network.py

@@ -40,7 +40,7 @@ def test_ip_get(mycharm):
         },
     )
 
-    with ctx.manager(
+    with ctx(
         ctx.on.update_status(),
         State(
             relations=[
@@ -77,7 +77,7 @@ def test_no_sub_binding(mycharm):
         },
     )
 
-    with ctx.manager(
+    with ctx(
         ctx.on.update_status(),
         State(
             relations=[
@@ -102,7 +102,7 @@ def test_no_relation_error(mycharm):
         },
     )
 
-    with ctx.manager(
+    with ctx(
         ctx.on.update_status(),
         State(
             relations=[

tests/test_e2e/test_pebble.py

@@ -128,9 +128,9 @@ def callback(self: CharmBase):
         charm_type=charm_cls,
         meta={"name": "foo", "containers": {"foo": {}}},
     )
-    with ctx.manager(ctx.on.start(), state=state) as mgr:
-        out = mgr.run()
-        callback(mgr.charm)
+    with ctx(ctx.on.start(), state=state) as event:
+        out = event.run()
+        callback(event.charm)
 
     if make_dirs:
         # file = (out.get_container("foo").mounts["foo"].source + "bar/baz.txt").open("/foo/bar/baz.txt")
@@ -318,8 +318,8 @@ def test_exec_wait_error(charm_cls):
     )
 
     ctx = Context(charm_cls, meta={"name": "foo", "containers": {"foo": {}}})
-    with ctx.manager(ctx.on.start(), state) as mgr:
-        container = mgr.charm.unit.get_container("foo")
+    with ctx(ctx.on.start(), state) as event:
+        container = event.charm.unit.get_container("foo")
         proc = container.exec(["foo"])
         with pytest.raises(ExecError):
             proc.wait()
@@ -340,8 +340,8 @@ def test_exec_wait_output(charm_cls):
     )
 
     ctx = Context(charm_cls, meta={"name": "foo", "containers": {"foo": {}}})
-    with ctx.manager(ctx.on.start(), state) as mgr:
-        container = mgr.charm.unit.get_container("foo")
+    with ctx(ctx.on.start(), state) as event:
+        container = event.charm.unit.get_container("foo")
         proc = container.exec(["foo"])
         out, err = proc.wait_output()
         assert out == "hello pebble"
@@ -360,8 +360,8 @@ def test_exec_wait_output_error(charm_cls):
     )
 
     ctx = Context(charm_cls, meta={"name": "foo", "containers": {"foo": {}}})
-    with ctx.manager(ctx.on.start(), state) as mgr:
-        container = mgr.charm.unit.get_container("foo")
+    with ctx(ctx.on.start(), state) as event:
+        container = event.charm.unit.get_container("foo")
         proc = container.exec(["foo"])
         with pytest.raises(ExecError):
             proc.wait_output()
@@ -381,10 +381,10 @@ def test_pebble_custom_notice(charm_cls):
 
     state = State(containers=[container])
     ctx = Context(charm_cls, meta={"name": "foo", "containers": {"foo": {}}})
-    with ctx.manager(
+    with ctx(
         ctx.on.pebble_custom_notice(container=container, notice=notices[-1]), state
-    ) as mgr:
-        container = mgr.charm.unit.get_container("foo")
+    ) as event:
+        container = event.charm.unit.get_container("foo")
         assert container.get_notices() == [n._to_ops() for n in notices]
 
 

tests/test_e2e/test_relations.py

@@ -417,8 +417,8 @@ def test_broken_relation_not_in_model_relations(mycharm):
     ctx = Context(
         mycharm, meta={"name": "local", "requires": {"foo": {"interface": "foo"}}}
     )
-    with ctx.manager(ctx.on.relation_broken(rel), state=State(relations={rel})) as mgr:
-        charm = mgr.charm
+    with ctx(ctx.on.relation_broken(rel), state=State(relations={rel})) as event:
+        charm = event.charm
 
         assert charm.model.get_relation("foo") is None
         assert charm.model.relations["foo"] == []

tests/test_e2e/test_resource.py

@@ -25,10 +25,10 @@ def test_get_resource():
     )
     resource1 = Resource(name="foo", path=pathlib.Path("/tmp/foo"))
     resource2 = Resource(name="bar", path=pathlib.Path("~/bar"))
-    with ctx.manager(
+    with ctx(
         ctx.on.update_status(), state=State(resources={resource1, resource2})
-    ) as mgr:
-        assert mgr.charm.model.resources.fetch("foo") == resource1.path
-        assert mgr.charm.model.resources.fetch("bar") == resource2.path
+    ) as event:
+        assert event.charm.model.resources.fetch("foo") == resource1.path
+        assert event.charm.model.resources.fetch("bar") == resource2.path
         with pytest.raises(NameError):
-            mgr.charm.model.resources.fetch("baz")
+            event.charm.model.resources.fetch("baz")