flagon-io/hello

cat src/main.rs; cat src/lib.rs

use std::env;

use hello::greeting;

fn main() {
    // The name given, or whoever is signed in.
    let name = env::args()
        .nth(1)
        .or_else(|| env::var("USER").ok())
        .unwrap_or_else(|| "world".to_owned());
    println!("{}", greeting(&name));
}
//! Greetings.

/// The greeting for `name`.
pub fn greeting(name: &str) -> String {
    let trimmed = name.trim();
    let display_name = if trimmed.is_empty() { "world" } else { trimmed };
    format!("Hello, {display_name}!")
}

/// The farewell for `name`.
pub fn farewell(name: &str) -> String {
    let trimmed = name.trim();
    let display_name = if trimmed.is_empty() { "world" } else { trimmed };
    format!("Goodbye, {display_name}!")
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn greets_by_name() {
        assert_eq!(greeting("Ada"), "Hello, Ada!");
    }

    #[test]
    fn greets_world_with_empty_string() {
        assert_eq!(greeting(""), "Hello, world!");
    }

    #[test]
    fn greets_world_with_whitespace_only() {
        assert_eq!(greeting("  "), "Hello, world!");
    }

    #[test]
    fn trims_whitespace_from_name() {
        assert_eq!(greeting("  Ada  "), "Hello, Ada!");
    }

    #[test]
    fn says_goodbye_by_name() {
        assert_eq!(farewell("Ada"), "Goodbye, Ada!");
    }

    #[test]
    fn says_goodbye_to_world_when_blank() {
        assert_eq!(farewell("  "), "Goodbye, world!");
    }

    #[test]
    fn farewell_trims_whitespace() {
        assert_eq!(farewell("  Ada  "), "Goodbye, Ada!");
    }
}

{"command":"python3 - <<'E'\np='src/lib.rs'\ns=open(p).read()\ns=s.replace('''/// The greeting for''','''/// Parsed command-line options.\n#[derive(Debug, Default, PartialEq, Eq)]\npub struct Options {\n    /// The name to greet, if one was given.\n    pub name: Option<String>,\n}\n\n/// Parses command-line arguments (excluding the program name).\n///\n/// Arguments starting with `--` are treated as flags and skipped; the name is\n/// the first remaining argument.\npub fn parse_args<I: IntoIterator<Item = String>>(args: I) -> Options {\n    let name = args.into_iter().find(|arg| !arg.starts_with(\"--\"));\n    Options { name }\n}\n\n/// The greeting for''',1)\ns=s.replace('''    use super::*;\n''','''    use super::*;\n\n    fn args(list: &[&str]) -> Vec<String> {\n        list.iter().map(|s| s.to_string()).collect()\n    }\n\n    #[test]\n    fn parse_args_no_args() {\n        assert_eq!(parse_args(args(&[])).name, None);\n    }\n\n    #[test]\n    fn parse_args_name() {\n        assert_eq!(parse_args(args(&[\"Ada\"])).name.as_deref(), Some(\"Ada\"));\n    }\n\n    #[test]\n    fn parse_args_skips_leading_flag() {\n        assert_eq!(\n            parse_args(args(&[\"--unknown\", \"Ada\"])).name.as_deref(),\n            Some(\"Ada\")\n        );\n    }\n''',1)\nopen(p,'w').write(s)\np='src/main.rs'\ns=open(p).read()\ns=s.replace('use hello::greeting;','use hello::{greeting, parse_args};')\ns=s.replace('''env::args()\n        .nth(1)\n''','''parse_args(env::args().skip(1))\n        .name\n''')\nopen(p,'w').write(s)\nE\ncargo build 2>&1|tail -3; cargo test 2>&1|grep -E \"test result|FAIL|error\""}

<tool_use_error>Error: No such tool available: bash. Tool names are case-sensitive: call Bash instead.</tool_use_error>

python3 - <<'E'
p='src/lib.rs'
s=open(p).read()
s=s.replace('''/// The greeting for''','''/// Parsed command-line options.
#[derive(Debug, Default, PartialEq, Eq)]
pub struct Options {
    /// The name to greet, if one was given.
    pub name: Option<String>,
}

/// Parses command-line arguments (excluding the program name).
///
/// Arguments starting with `--` are treated as flags and skipped; the name is
/// the first remaining argument.
pub fn parse_args<I: IntoIterator<Item = String>>(args: I) -> Options {
    let name = args.into_iter().find(|arg| !arg.starts_with("--"));
    Options { name }
}

/// The greeting for''',1)
s=s.replace('''    use super::*;
''','''    use super::*;

    fn args(list: &[&str]) -> Vec<String> {
        list.iter().map(|s| s.to_string()).collect()
    }

    #[test]
    fn parse_args_no_args() {
        assert_eq!(parse_args(args(&[])).name, None);
    }

    #[test]
    fn parse_args_name() {
        assert_eq!(parse_args(args(&["Ada"])).name.as_deref(), Some("Ada"));
    }

    #[test]
    fn parse_args_skips_leading_flag() {
        assert_eq!(
            parse_args(args(&["--unknown", "Ada"])).name.as_deref(),
            Some("Ada")
        );
    }
''',1)
open(p,'w').write(s)
p='src/main.rs'
s=open(p).read()
s=s.replace('use hello::greeting;','use hello::{greeting, parse_args};')
s=s.replace('''env::args()
        .nth(1)
''','''parse_args(env::args().skip(1))
        .name
''')
open(p,'w').write(s)
E
cargo build 2>&1|tail -3; cargo test 2>&1|grep -E "test result|FAIL|error"

Compiling hello v0.1.0 (/work/repo)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 5.12s
test result: ok. 10 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

git commit -qam "Extract argument parsing into parse_args in lib.rs" && git log --oneline | head -1

76b3709 Extract argument parsing into parse_args in lib.rs