Minor fixes based on review.

README.md

@@ -664,8 +664,8 @@ def test_pebble_exec():
         ctx.on.pebble_ready(container),
         state_in,
     )
-    assert ctx.exec_history[container.name].command == ['ls', '-ll']
-    assert ctx.exec_history[container.name].stdin == "..."
+    assert ctx.exec_history[container.name][0].command == ['ls', '-ll']
+    assert ctx.exec_history[container.name][0].stdin == "..."
 ```
 
 Scenario will attempt to find the right `Exec` object by matching the provided

scenario/context.py

@@ -1,13 +1,13 @@
 #!/usr/bin/env python3
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
-import collections
 import tempfile
 from contextlib import contextmanager
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Type, Union, cast
 
 from ops import CharmBase, EventBase
+from ops.testing import ExecArgs
 
 from scenario.logger import logger as scenario_logger
 from scenario.runtime import Runtime
@@ -451,7 +451,7 @@ def __init__(
         self.juju_log: List["JujuLogLine"] = []
         self.app_status_history: List["_EntityStatus"] = []
         self.unit_status_history: List["_EntityStatus"] = []
-        self.exec_history = collections.defaultdict(list)
+        self.exec_history: Dict[str, List[ExecArgs]] = {}
         self.workload_version_history: List[str] = []
         self.removed_secret_revisions: List[int] = []
         self.emitted_events: List[EventBase] = []

scenario/mocking.py

@@ -844,19 +844,22 @@ def exec(
             stderr.write(handler.stderr)
 
         args = ExecArgs(
-            command,
-            environment or {},
-            working_dir,
-            timeout,
-            user_id,
-            user,
-            group_id,
-            group,
-            stdin,  # type:ignore  # If None, will be replaced by proc_stdin.read() later.
-            encoding,
-            combine_stderr,
+            command=command,
+            environment=environment or {},
+            working_dir=working_dir,
+            timeout=timeout,
+            user_id=user_id,
+            user=user,
+            group_id=group_id,
+            group=group,
+            stdin=stdin,  # type:ignore  # If None, will be replaced by proc_stdin.read() later.
+            encoding=encoding,
+            combine_stderr=combine_stderr,
         )
-        self._context.exec_history[self._container_name].append(args)
+        try:
+            self._context.exec_history[self._container_name].append(args)
+        except KeyError:
+            self._context.exec_history[self._container_name] = [args]
 
         change_id = handler._run()
         return cast(