# Macro std::assert_matches
[−][src]

    macro_rules! assert_matches {
         => { ... };
         => { ... };
    }

🔬 This is a nightly-only experimental API. (`assert_matches` #82775)

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)]

    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