Function findings 

pub fn findings(
    registry: &CapabilityRegistry,
    tree: &CommandDoc,
) -> Vec<Finding>

Every unmet claim, in capability order, then in projection order.

Pure: the registry and the clap tree, nothing read from disk. An empty result is the closure the rule asks for.

// the command line this crate declares answers every claim made about it
let registry = CapabilityRegistry::builder()
    .with_modules(majordomus_cli::capability::builtin::modules())
    .build()
    .expect("the builtin registry builds");
assert!(closure::findings(&registry, &majordomus_cli::cli::tree()).is_empty());