import pytest
from src.commands import COMMANDS


def test_help_returns_nonempty_string():
    result = COMMANDS["help"]()
    assert isinstance(result, str)
    assert len(result) > 0


def test_help_mentions_help_command():
    result = COMMANDS["help"]()
    assert "help" in result


def test_unknown_command_not_in_registry():
    assert "foobar" not in COMMANDS


def test_all_commands_are_callable():
    for name, handler in COMMANDS.items():
        assert callable(handler), f"Command '{name}' is not callable"


def test_exit_raises_system_exit(capsys):
    with pytest.raises(SystemExit) as exc_info:
        COMMANDS["exit"]()
    assert exc_info.value.code == 0


def test_exit_prints_goodbye(capsys):
    with pytest.raises(SystemExit):
        COMMANDS["exit"]()
    captured = capsys.readouterr()
    assert "Goodbye!" in captured.out


def test_exit_is_in_registry():
    assert "exit" in COMMANDS


def test_help_mentions_exit():
    result = COMMANDS["help"]()
    assert "exit" in result