Macro core::assert_matches::assert_matches [−][src]
pub macro assert_matches {
($left : expr, $(|) ? $($pattern : pat_param) | + $(if $guard : expr) ? $(,)
?) => { ... },
($left : expr, $(|) ? $($pattern : pat_param) | + $(if $guard : expr) ?,
$($arg : tt) +) => { ... },
}
Expand description
Asserts that an expression matches any of the given patterns.
Like in a match
expression, the pattern can be optionally followed by if
and a guard expression that has access to names bound by the pattern.
On panic, this macro will print the value of the expression with its debug representation.
Like assert!
, this macro has a second form, where a custom
panic message can be provided.
Examples
#![feature(assert_matches)]
use std::assert_matches::assert_matches;
let a = 1u32.checked_add(2);
let b = 1u32.checked_sub(2);
assert_matches!(a, Some(_));
assert_matches!(b, None);
let c = Ok("abc".to_string());
assert_matches!(c, Ok(x) | Err(x) if x.len() < 100);
Run