ros2node: Add verb get_type_description

Adds the verb `get_type_description` which calls the given node's
~/get_type_description service and prints out the response.
This verb is basically a shorthand for
`ros2 service call <node>/get_type_description ...`.

ros2node/package.xml

@@ -20,6 +20,7 @@
   <depend>ros2cli</depend>
 
   <exec_depend>rclpy</exec_depend>
+  <exec_depend>rosidl_runtime_py</exec_depend>
 
   <test_depend>ament_copyright</test_depend>
   <test_depend>ament_flake8</test_depend>

ros2node/ros2node/verb/get_type_description.py

@@ -0,0 +1,64 @@
+# Copyright 2023 Open Source Robotics Foundation, Inc.
+#
+# 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.
+
+import rclpy
+from ros2cli.node import NODE_NAME_PREFIX
+from ros2node.api import NodeNameCompleter
+from ros2node.verb import VerbExtension
+from rosidl_runtime_py import message_to_yaml
+from type_description_interfaces.srv import GetTypeDescription
+
+
+class GetTypeDescriptionVerb(VerbExtension):
+    """Call a node's ~/get_type_description service and print the response."""
+
+    def add_arguments(self, parser, cli_name):
+        argument = parser.add_argument(
+            'node_name',
+            help='Node name to request information')
+        argument.completer = NodeNameCompleter()
+        argument = parser.add_argument(
+            'type_name',
+            help='ROS interface type name, in PACKAGE/NAMESPACE/TYPENAME format')
+        argument = parser.add_argument(
+            'type_hash',
+            help='REP-2011 RIHS hash string')
+        argument = parser.add_argument(
+            '--include_type_sources', default=False, action='store_true',
+            help='Whether to return the original idl/msg/etc. source file(s) in the response')
+
+    def main(self, *, args):
+        rclpy.init()
+        node = rclpy.create_node(NODE_NAME_PREFIX + '_requester_%s_%s' %
+                                 ('type_description_interfaces', 'GetTypeDescription'))
+
+        service_name = args.node_name + '/get_type_description'
+        cli = node.create_client(GetTypeDescription, service_name)
+
+        if not cli.service_is_ready():
+            print(f'waiting for service {service_name} to become available...')
+            cli.wait_for_service()
+
+        request = GetTypeDescription.Request(type_name=args.type_name,
+                                             type_hash=args.type_hash,
+                                             include_type_sources=args.include_type_sources)
+        future = cli.call_async(request)
+        rclpy.spin_until_future_complete(node, future)
+        if future.result() is not None:
+            print(message_to_yaml(future.result()))
+        else:
+            raise RuntimeError('Exception while calling service: %r' % future.exception())
+
+        node.destroy_node()
+        rclpy.shutdown()

ros2node/setup.py

@@ -42,6 +42,7 @@
         'ros2node.verb': [
             'info = ros2node.verb.info:InfoVerb',
             'list = ros2node.verb.list:ListVerb',
+            'get_type_description = ros2node.verb.get_type_description:GetTypeDescriptionVerb',
         ],
     }
 )

ros2node/test/test_cli.py

@@ -229,3 +229,44 @@ def test_info_hidden_node_hidden_flag(self):
             ]),
             text=node_command.output, strict=False
         ), 'Output does not match:\n' + node_command.output
+
+    @launch_testing.markers.retry_on_failure(times=5, delay=1)
+    def test_get_type_description_invalid_hash(self):
+        arguments = ['get_type_description', '/complex_node', 'some_type', 'some_hash']
+        with self.launch_node_command(arguments=arguments) as node_command:
+            assert node_command.wait_for_shutdown(timeout=10)
+        assert node_command.exit_code == launch_testing.asserts.EXIT_OK
+        assert launch_testing.tools.expect_output(
+            expected_lines=itertools.chain([
+                'successful: false',
+                re.compile(r'failure_reason: .*'),
+                'type_description:',
+                '  type_description:',
+                '    type_name: ''',
+                '    fields: []',
+                '  referenced_type_descriptions: []',
+                'type_sources: []',
+                'extra_information: []',
+            ]),
+            text=node_command.output, strict=False
+        ), 'Output does not match:\n' + node_command.output
+
+    @launch_testing.markers.retry_on_failure(times=5, delay=1)
+    def test_get_type_description_valid_hash(self):
+        arguments = [
+            'get_type_description',
+            '/complex_node',
+            'test_msgs.msg.Arrays',
+            # Type hash below is from test_msgs/share/test_msgs/msg/Arrays.json
+            'RIHS01_8a321b80dae8c44dfd1ce558eaf1b1cd5ebbe5950863ed675836535511a7f91a'
+        ]
+        with self.launch_node_command(arguments=arguments) as node_command:
+            assert node_command.wait_for_shutdown(timeout=10)
+        assert node_command.exit_code == launch_testing.asserts.EXIT_OK
+        assert launch_testing.tools.expect_output(
+            expected_lines=itertools.chain([
+                'successful: true',
+                "failure_reason: ''",
+            ]),
+            text=node_command.output, strict=False
+        ), 'Output does not match:\n' + node_command.output