Function xpct::be_err

pub fn be_err<'a, T, E>() -> Matcher<'a, Result<T, E>, E, T>where
    T: Debug + 'a,
    E: Debug + 'a,

Succeeds when the actual value is Err.

If this matcher succeeds, it unwraps the Err value. When negated, it behaves like be_ok.

Examples

use std::io;
use xpct::{expect, equal, be_err};

fn might_fail() -> io::Result<()> {
    Err(io::Error::new(io::ErrorKind::Other, "something bad happened"))
}

expect!(might_fail())
    .to(be_err())
    .map(|err| err.kind())
    .to(equal(io::ErrorKind::Other));