def METHOD_NAME(build_command, first_app_config, capsys):
    """An unknown system can't be verified."""
    first_app_config.target_vendor_base = "somevendor"
    build_command.verify_system_packages(first_app_config)
    # No packages verified
    build_command.tools.subprocess.check_output.assert_not_called()
    # A warning was logged.
    output = capsys.readouterr().out
    assert "WARNING: Can't verify system packages" in output