Add typed base command classes for OSC commands

Add ironicclient/osc/command.py with Command, Lister, and ShowOne
subclasses that annotate ``app`` so that
``self.app.client_manager.baremetal`` is a known attribute, removing
the need for ``# type: ignore[attr-defined]`` in command
implementations. This follows the same pattern as
python-openstackclient (see review.opendev.org/970681).

Also add collections.abc and typing to [hacking] import_exceptions
in tox.ini, allowing multi-name imports on a single line (matching
the Nova convention).

Change-Id: Ifebbbf5ed5d58e1d5e918ae7b426f1cf0f42f135
Signed-off-by: Karan Anand <anandkarancompsci@gmail.com>

ironicclient/osc/command.py

@@ -0,0 +1,58 @@
+#   Licensed under the Apache License, Version 2.0 (the "License"); you may
+#   not use this file except in compliance with the License. You may obtain
+#   a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#   License for the specific language governing permissions and limitations
+#   under the License.
+
+"""Typed base command classes for ironicclient OSC commands.
+
+These subclass osc-lib's command classes and annotate ``app`` so that
+``self.app.client_manager.baremetal`` is statically known to be
+:class:`ironicclient.v1.client.Client`, removing the need for
+``# type: ignore[attr-defined]`` throughout the command implementations.
+
+See https://review.opendev.org/c/openstack/python-openstackclient/+/970681
+for the equivalent pattern in python-openstackclient.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from cliff import lister
+from cliff import show
+from osc_lib import clientmanager
+from osc_lib.command import command
+from osc_lib import shell
+
+
+class _ClientManager(clientmanager.ClientManager):
+    # NOTE(karan): baremetal is injected dynamically by the plugin
+    # system (via setattr in osc-lib's get_plugin_modules). Typed as
+    # Any because osc-lib's utility functions (e.g. get_item_properties)
+    # have narrow type signatures that don't accept Resource objects.
+    # Can be narrowed to v1.client.Client once those callers are
+    # updated.
+    baremetal: Any
+
+
+class _App(shell.OpenStackShell):
+    client_manager: _ClientManager
+
+
+class Command(command.Command):
+    app: _App
+
+
+class Lister(Command, lister.Lister):
+    pass
+
+
+class ShowOne(Command, show.ShowOne):
+    pass

tox.ini

@@ -82,7 +82,11 @@ import-order-style = pep8
 application-import-names = ironicclient
 
 [hacking]
-import_exceptions = testtools.matchers, ironicclient.common.i18n
+import_exceptions =
+  collections.abc
+  ironicclient.common.i18n
+  testtools.matchers
+  typing
 
 [testenv:codespell]
 description =