Sample

Build and test a package:args CommandRunner subcommand CLI, telling apart which node reports a UsageException and pinning the option rules that differ from argparse, getopt and clap

sha256:d5e47381de03ab961e2135483018d410dd3e1365963e163f552519d3a16f7875

Case

Goal

Build and test a package:args CommandRunner subcommand CLI, telling apart which node reports a UsageException and pinning the option rules that differ from argparse, getopt and clap HOW

Packages

args 2.7.0

Environment

dart 3

Created

2026-08-14T19:59:28Z

Contract

• assert a subcommand runs and the value its run returns comes back out of CommandRunner<int>.run, so the exit code travels as a return value and nothing is printed
• assert no arguments, --help and <command> --help all complete with null after printing usage, so null is a success value and Command.run was never reached
• assert an unknown command is a UsageException whose usage is the runner's, with Global options and Available commands, whose toString is message and usage joined, and whose message gains an edit-distance suggestion block only within the default limit of 2
• assert a parse error inside a subcommand is the same UsageException type carrying that subcommand's usage instead of the command list, while a stray word before the command name is reported by the top-level parser and carries the runner's usage again
• assert a unique prefix of a long option is simply an unknown option, because long names are resolved by exact name or alias and no switch adds prefix matching, while the single-letter abbr and an exact alias both work and the alias stays out of the usage block
• assert a collapsed run of single letters takes its value on the FIRST letter, so -tprod sets the option and -vtprod and -vt prod both fail because a later letter must be a flag, and that an unknown letter has one message alone and a different one inside a run
• assert mandatory: true is enforced during parsing only when the option also declares a callback, and that without one the parse succeeds and leaves the option out of the results entirely
• assert the callback-less mandatory option therefore fails as an ArgumentError from ArgResults.option after the command body has already started, while the same declaration with a callback fails as a UsageException during parsing before run is reached
• assert the required option that behaves the same either way is a null check plus an explicit usageException call, throwing UsageException with that command's usage
• assert addFlag creates --no-x for free, including for a flag that already defaults to false, that negatable: false turns --no-x into an error naming the spelling that was typed rather than the declared flag, and that the usage block renders the difference as --[no-]x
• assert everything after -- lands in rest unparsed so a flag past it does not take effect, and that only the first -- is consumed
• assert a -- before the command name stops the top-level parser before it ever looks the command up, so the command that was asked for is reported as unknown while being suggested back

Files

• csx.json
• lib/cli.dart
• pubspec.lock
• pubspec.yaml
• test/contract_test.dart

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

anonymous

Verification receipts

• dart 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-14 · ed25519:a2ec939a4c60e243