extern crate clap; use clap::App; #[test] fn print_app_help() { let mut app = App::new("test") .author("Kevin K.") .about("tests stuff") .version("1.3") .args_from_usage("-f, --flag 'some flag' --option [opt] 'some option'"); // We call a get_matches method to cause --help and --version to be built let _ = app.get_matches_from_safe_borrow(vec![""]); // Now we check the output of print_help() let mut help = vec![]; app.write_help(&mut help).ok().expect("failed to print help"); assert_eq!(&*String::from_utf8_lossy(&*help), &*String::from("test 1.3\n\ Kevin K. tests stuff USAGE: \ttest [FLAGS] [OPTIONS] FLAGS: -f, --flag some flag -h, --help Prints help information -V, --version Prints version information OPTIONS: --option some option\n")); }