err-test.rs

#[test]
fn check_reference_error() {
    let result = check_and_get_result("var x = 5; y;");
    let errors = result.unwrap_err();
    assert_eq!(errors.len(), 1);
    let &(ref error, ref span) = errors.get(0).unwrap();
    assert_eq!(*error, TypeCheckerIssue::InterpreterError(InterpreterError::ReferenceError("y".to_owned())));
}

Ideally, what I would like to express this as is:

assert_eq!(
    errors,
    vec![InterpreterError::ReferenceError("y".to_owned()).into()]
);