Minor regression introduced in help functionality in typer==0.12.2

[mattkram]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
• I searched the Typer documentation, with the integrated search.
• I already searched in Google "How to X in Typer" and didn't find any information.
• I already read and followed all the tutorials in the docs and didn't find an answer.
• I already checked if it is not related to Typer but to Click.

Commit to Help

• I commit to help with one of those options 👆

Example Code

from typer import Typer
from typer.testing import CliRunner


app = Typer(help="My cool Typer app!")


@app.callback(invoke_without_command=True, no_args_is_help=True)
def main() -> None:
    return None

# Comment below and the bug no longer occurs
#@app.command()
#def hello():
#    return None


runner = CliRunner()
result = runner.invoke(app, ["--help"])

# We expect the exit code to be 0, but it will return exit_code 1 and an exception
assert result.exit_code == 0, result.exception

Description

There is a small regression introduced in #567. If a Typer instance is defined without any commands, but with a callback, a ValueError is raised when asking for the help text: max() arg is an empty sequence.

I tracked the problem down to this code.

The fix is to add a check that commands has at least one item. If a command is added, then the issue is resolved.

I have not reviewed the source completely yet to know what a default command length should be, but I will and I am happy to contribute a fix.

Operating System

macOS

Operating System Details

No response

Typer Version

0.12.2

Python Version

3.10.14

Additional Context

No response

[svlandeg]

Thanks for the report and the reproducable code! This is fixed by #796 and I used your code to create a unit test for it 🙏

[mattkram]

Thanks!

[tiangolo]

The fix is now available in Typer 0.12.3 🚀