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//! How to use `required_if` with structopt.
//!
//! Running this example with --help prints this message:
//! -----------------------------------------------------
//! structopt 0.3.25
//!
//! USAGE:
//! required_if -o <out-type> [FILE]
//!
//! FLAGS:
//! -h, --help Prints help information
//! -V, --version Prints version information
//!
//! OPTIONS:
//! -o <out-type> Where to write the output: to `stdout` or `file`
//!
//! ARGS:
//! <FILE> File name: only required when `out-type` is set to `file`
//! -----------------------------------------------------
use structopt::StructOpt;
#[derive(Debug, StructOpt, PartialEq)]
struct Opt {
/// Where to write the output: to `stdout` or `file`
#[structopt(short)]
out_type: String,
/// File name: only required when `out-type` is set to `file`
#[structopt(name = "FILE", required_if("out-type", "file"))]
file_name: Option<String>,
}
fn main() {
let opt = Opt::from_args();
println!("{:?}", opt);
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_opt_out_type_file_without_file_name_returns_err() {
let opt = Opt::from_iter_safe(&["test", "-o", "file"]);
let err = opt.unwrap_err();
assert_eq!(err.kind, clap::ErrorKind::MissingRequiredArgument);
}
#[test]
fn test_opt_out_type_file_with_file_name_returns_ok() {
let opt = Opt::from_iter_safe(&["test", "-o", "file", "filename"]);
let opt = opt.unwrap();
assert_eq!(
opt,
Opt {
out_type: "file".into(),
file_name: Some("filename".into()),
}
);
}
}
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