I am trying to check the return value of the result_callback of my cli. In the code below I can check the stdout, but I want the actual value returned.

Does anyone know how to get the output value of the result_callback when testing?

import click
from click.testing import CliRunner


@click.group()
def main():
    pass


@main.command()
@click.argument("name")
def hello(name):
    return name


@main.result_callback()
def process_result(result):
    result = "".join(reversed(result))
    click.echo(f"Hello {result}!")
    return result


def test_hello_world():
    runner = CliRunner()
    observed = runner.invoke(main, ["hello", "Peter"])
    assert observed.exit_code == 0
    assert observed.output == "Hello reteP!n"
    # assert observed.callback_value == "reteP" # how to do this???