Macro test_none 

macro_rules! test_none {
    (
    $($target:tt)*
) => { ... };
}

Wraps a function that takes nothing and returns something, failing the test if the result is not None. Shortcut for should_none!.

// This macro invocation:
test_none! { ... }
// Is equivalent to:
should_none! { #[test] ... }