Simplify the task interface and rename back to ActionOutput.

README.md

@@ -977,15 +977,15 @@ def test_backup_action():
     state = ctx.run(ctx.on.action("do_backup"), scenario.State())
 
     # You can assert action results and logs using the action history:
-    assert ctx.action_history[0].logs == ['baz', 'qux']
-    assert ctx.action_history[0].results == {'foo': 'bar'}
+    assert ctx.action_output.logs == ['baz', 'qux']
+    assert ctx.action_output.results == {'foo': 'bar'}
 ```
 
 ## Failing Actions
 
 If the charm code calls `event.fail()` to indicate that the action has failed,
 an `ActionFailed` exception will be raised. This avoids having to include
-`assert ctx.action_history[0].status == "completed"` code in every test where
+`assert ctx.action_output.status == "completed"` code in every test where
 the action is successful.
 
 ```python
@@ -997,8 +997,8 @@ def test_backup_action_failed():
     assert exc_info.value.message == "sorry, couldn't do the backup"
 
     # You can still assert action results and logs that occured before the failure:
-    assert ctx.action_history[0].logs == ['baz', 'qux']
-    assert ctx.action_history[0].results == {'foo': 'bar'}
+    assert ctx.action_output.logs == ['baz', 'qux']
+    assert ctx.action_output.results == {'foo': 'bar'}
 ```
 
 ## Parametrized Actions

scenario/__init__.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
-from scenario.context import Context, Manager, Task
+from scenario.context import ActionOutput, Context, Manager
 from scenario.state import (
     ActionFailed,
     ActiveStatus,
@@ -39,7 +39,7 @@
 )
 
 __all__ = [
-    "Task",
+    "ActionOutput",
     "ActionFailed",
     "CheckInfo",
     "CloudCredential",

scenario/context.py

@@ -39,11 +39,11 @@
 
 
 @dataclasses.dataclass(frozen=True)
-class Task(_max_posargs(0)):
+class ActionOutput(_max_posargs(0)):
     """Wraps the results of running an action event on a unit.
 
     Tests should generally not create instances of this class directly, but
-    rather use the :attr:`Context.action_history` attribute to inspect the
+    rather use the :attr:`Context.action_output` attribute to inspect the
     results of running actions.
     """
 
@@ -496,7 +496,7 @@ def __init__(
         self._output_state: Optional["State"] = None
 
         # operations (and embedded tasks) from running actions
-        self.action_history: List[Task] = []
+        self.action_output: Optional[ActionOutput] = None
 
         self.on = _CharmEvents()
 
@@ -563,11 +563,12 @@ def run(self, event: "_Event", state: "State") -> "State":
             charm will invoke when handling the Event.
         """
         if event.action:
-            self.action_history.append(Task())
+            self.action_output = ActionOutput()
         with self._run(event=event, state=state) as ops:
             ops.emit()
         if event.action:
-            current_task = self.action_history[-1]
+            current_task = self.action_output
+            assert current_task is not None
             if current_task.status == "failed":
                 raise ActionFailed(current_task.failure_message, self.output_state)
             current_task.set_status("completed")

scenario/mocking.py

@@ -528,22 +528,25 @@ def action_set(self, results: Dict[str, Any]):
         _format_action_result_dict(results)
         # but then we will store it in its unformatted,
         # original form for testing ease
-        self._context.action_history[-1].update_results(results)
+        assert self._context.action_output is not None
+        self._context.action_output.update_results(results)
 
     def action_fail(self, message: str = ""):
         if not self._event.action:
             raise ActionMissingFromContextError(
                 "not in the context of an action event: cannot action-fail",
             )
-        self._context.action_history[-1].set_status("failed")
-        self._context.action_history[-1].set_failure_message(message)
+        assert self._context.action_output is not None
+        self._context.action_output.set_status("failed")
+        self._context.action_output.set_failure_message(message)
 
     def action_log(self, message: str):
         if not self._event.action:
             raise ActionMissingFromContextError(
                 "not in the context of an action event: cannot action-log",
             )
-        self._context.action_history[-1].logs.append(message)
+        assert self._context.action_output is not None
+        self._context.action_output.logs.append(message)
 
     def action_get(self):
         action = self._event.action

scenario/state.py

@@ -1853,7 +1853,7 @@ def test_backup_action():
                 ctx.on.action('do_backup', params={'filename': 'foo'}),
                 scenario.State()
             )
-            assert ctx.action_history[0].results == ...
+            assert ctx.action_output.results == ...
     """
 
     name: str

tests/test_context.py

@@ -3,7 +3,7 @@
 import pytest
 from ops import CharmBase
 
-from scenario import Context, State, Task
+from scenario import ActionOutput, Context, State
 from scenario.state import _Event, next_action_id
 
 
@@ -70,9 +70,9 @@ def test_context_manager():
         assert mgr.charm.meta.name == "foo"
 
 
-def test_task_no_positional_arguments():
+def test_action_output_no_positional_arguments():
     with pytest.raises(TypeError):
-        Task(None)
+        ActionOutput(None)
 
 
 def test_action_output_no_results():
@@ -86,8 +86,7 @@ def _on_act_action(self, _):
 
     ctx = Context(MyCharm, meta={"name": "foo"}, actions={"act": {}})
     ctx.run(ctx.on.action("act"), State())
-    assert len(ctx.action_history) == 1
-    task = ctx.action_history[0]
-    assert task.results is None
-    assert task.status == "completed"
-    assert task.failure_message == ""
+    action_output = ctx.action_output
+    assert action_output.results is None
+    assert action_output.status == "completed"
+    assert action_output.failure_message == ""

tests/test_e2e/test_actions.py

@@ -68,9 +68,8 @@ def handle_evt(_: CharmBase, evt):
 
     ctx.run(ctx.on.action("foo"), State())
 
-    assert len(ctx.action_history) == 1
-    assert ctx.action_history[0].results == res_value
-    assert ctx.action_history[0].status == "completed"
+    assert ctx.action_output.results == res_value
+    assert ctx.action_output.status == "completed"
 
 
 @pytest.mark.parametrize("res_value", ({"a": {"b": {"c"}}}, {"d": "e"}))
@@ -90,8 +89,7 @@ def handle_evt(_: CharmBase, evt: ActionEvent):
     with pytest.raises(ActionFailed) as out:
         ctx.run(ctx.on.action("foo"), State())
     assert out.value.message == "failed becozz"
-    assert len(ctx.action_history) == 1
-    task = ctx.action_history[0]
+    task = ctx.action_output
     assert task.results == {"my-res": res_value}
     assert task.logs == ["log1", "log2"]
     assert task.failure_message == "failed becozz"
@@ -114,8 +112,8 @@ def _on_foo_action(self, event):
     with pytest.raises(ActionFailed) as exc_info:
         ctx.run(ctx.on.action("foo"), State())
     assert exc_info.value.message == "oh no!"
-    assert ctx.action_history[0].logs == ["starting"]
-    assert ctx.action_history[0].results == {"initial": "result", "final": "result"}
+    assert ctx.action_output.logs == ["starting"]
+    assert ctx.action_output.results == {"initial": "result", "final": "result"}
 
 
 def _ops_less_than(wanted_major, wanted_minor):