Macro check 

macro_rules! check {
    ($m:ident => $($(#[doc = $doc:expr])?$name:ident$((passes: $($($pass:literal);*),* fails: $($($fail:literal);*),*))?: |$($param:ident$(, $(_$unused:tt)?)?)+| $check:expr)*) => { ... };
}

Defines a new check, and also generates docs/tests for example input of the check.

Example:

#![feature(generic_const_exprs)]

checks::check! { u8 =>
    /// Matches all binary numbers (0, 1)
    Binary(
        passes: 0, 1
        fails: 2, 3, 4
    ): |N| (N == 0 || N == 1)
}