Sample

Define and test a clap 4 derive CLI across the #[clap] to #[command] and #[arg] attribute split, checking outcomes with try_parse_from and ErrorKind instead of a process

sha256:6e0aceb749a7c19cc2aa7a185f5f9cac427fedb08e50c9afc51b0c69de42d116

Case

Goal

Define and test a clap 4 derive CLI across the #[clap] to #[command] and #[arg] attribute split, checking outcomes with try_parse_from and ErrorKind instead of a process HOW

Packages

clap 4.6.6

Environment

rust 1

Created

2026-08-14T08:54:45Z

Contract

• assert the command name comes from the attribute on the struct while every argument id comes from a field and its attribute
• assert help and version are absent from the Command until Command::build injects them, and that parsing performs that build for you
• assert the clap 3 #[clap(...)] spelling still compiles under clap 4, naming the command on the struct and declaring the argument on a field
• assert a minimal invocation fills default_value_t and leaves an Option<T> option as None
• assert dropping the program name from try_parse_from makes the first real argument the program name in the usage line and reports a missing required argument
• assert -o value, --output value, --output=value and the attached -ovalue all set the same option
• assert ArgAction::Count turns -vvv into 3 and -v -v into 2
• assert -V is the version flag while -v stays the verbose counter
• assert ValueEnum renders variants in kebab-case and that pretty_json, PrettyJson and JSON are ErrorKind::InvalidValue
• assert an unknown flag is ErrorKind::UnknownArgument and that the rendered error carries the tip naming the real --output
• assert a missing required positional is ErrorKind::MissingRequiredArgument
• assert both real errors exit 2 and go to stderr
• assert --help and -h are ErrorKind::DisplayHelp with exit code 0 on stdout, not a parse failure
• assert the rendered help shows the default value and the possible values
• assert --version is ErrorKind::DisplayVersion carrying the version from the command attribute

Files

• Cargo.lock
• Cargo.toml
• csx.json
• src/main.rs

Origin Seeder

anonymous

Verification receipts

• rust 1 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · cargo@1 · 2026-08-14 · ed25519:a2ec939a4c60e243
• · CONTAINER_RUN · compile:SKIPPED · contract:FAIL · load:SKIPPED · resolve:PASS · cargo@1 · 2026-08-14 · ed25519:7da3f610facce8bf