Add --remap argument to launch command

[JoLichtenfeld]

This adds the option to specify remapping rules for launch files in the launch command.

Example: ros2 launch <launch_file> --remap topic1:=new1 --remap topic2:=new2

[fujitatomoya]

i believe that would be really nice to have the ros2launch test aligns with this enhancement.

[fujitatomoya]

@JoLichtenfeld could you consider if we can add the test case for this?

[JoLichtenfeld]

I will come up with a test case as soon as I find the time for it.

[kramer-sim]

@fujitatomoya Hi, in which directory should the test be placed? Do you want that we write the test cases in /ros2launch/test?
Should it be similar to the test cases in https://github.com/ros2/ros2cli/blob/f5e5a798d57c437410452f2b106f115d3a42c7a2/ros2cli/test/test_ros2cli_direct.py#L45C1-L48C34 or do you want to actually start a launch file on the command line and check whether the remapping works?
You can find an example of that below:

    def test_remap_argument(self):
        """Test that the --remap argument correctly remaps topics."""

        try:
            # Start the talker_listener launch file with remapping
            launch_proc_remapped = subprocess.Popen(
                ['ros2', 'launch', 'demo_nodes_cpp', 'talker_listener_launch.py', 
                 '--remap', '/chatter:=/chatter_remapped'],
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE
            )

            # Run ros2 topic list to get the remapped topics
            result = subprocess.run(['ros2', 'topic', 'list'], 
                                  stdout=subprocess.PIPE, 
                                  stderr=subprocess.PIPE, 
                                  text=True, 
                                  check=True)
            remapped_topics = result.stdout.strip().split('\n')

            # Verify /chatter is NOT in the list
            self.assertNotIn('/chatter', remapped_topics, 
                           f"Did not expect to find /chatter after remapping. Topics: {remapped_topics}")

            # Verify /chatter_remapped IS in the list
            self.assertIn('/chatter_remapped', remapped_topics, 
                        f"Expected to find /chatter_remapped after remapping. Topics: {remapped_topics}")

        finally:
            # Clean up
            if 'launch_proc_remapped' in locals():
                launch_proc_remapped.terminate()
                try:
                    launch_proc_remapped.wait(timeout=5)
                except subprocess.TimeoutExpired:
                    launch_proc_remapped.kill()
                    launch_proc_remapped.wait()


if __name__ == '__main__':
    unittest.main()

[fujitatomoya]

do you want to actually start a launch file on the command line and check whether the remapping works?

probably this one? because it actually verifies that this arguments work with launch.
https://github.com/ros2/launch_ros/tree/rolling/ros2launch/test is suitable place to put the test codes for ros2launch.

[kramer-sim]

@fujitatomoya It appears that the test environment is missing the ROS 2 CLI extensions that provide the topic command. Only a limited set of commands are available, see this error message:

test/test_cli_remap.py:55: in test_remap_argument
    self.fail(f"'ros2 topic list' command failed with error: {result.stderr}")
E   AssertionError: 'ros2 topic list' command failed with error: usage: ros2 [-h] [--use-python-default-buffering]
E               Call `ros2 <command> -h` for more detailed usage. ...
E   ros2: error: argument Call `ros2 <command> -h` for more detailed usage.: invalid choice: 'topic' (choose from 'daemon', 'extension_points', 'extensions', 'pkg')

Do you have any recommendations how to proceed?

[fujitatomoya]

@Mergifyio rebase

[mergify]

rebase

✅ Branch has been successfully rebased

[fujitatomoya]

@ros-pull-request-builder retest this please