Function xpct::why

pub fn why<'a, In, PosOut, NegOut>(
    matcher: Matcher<'a, In, PosOut, NegOut>,
    reason: impl Into<Cow<'a, str>>
) -> Matcher<'_, In, PosOut, NegOut>where
    In: 'a,
    PosOut: 'a,
    NegOut: 'a,

Attaches a context string to a matcher that will appear in the failure output.

Examples

use xpct::{expect, why, be_ge};

let index = 2_i32;

expect!(index).to(why(
    be_ge(0),
    "indices must be positive"
));