Trait AssertErrExt 

pub trait AssertErrExt {
    // Required methods
    fn assert_err(self) -> Self;
    fn debug_assert_err(self) -> Self;
}

An extension trait to add the assertion_err methods.

Required Methods

fn assert_err(self) -> Self

Asserts the Result is Err.

Panics

If it is Ok, the method panics.

Examples

This sample

use chain_assertions::prelude::*;

let x: Result<&str, i32> = Err(21);
let x = x.assert_err().map_err(|v| v * 2);
assert_eq!(x, Err(42));

use chain_assertions::prelude::*;

let x: Result<&str, i32> = Ok("success");
let _ = x.assert_err().map_err(|v| v * 2);
//        ^-- panics here

fn debug_assert_err(self) -> Self

Asserts the Result is Err only in debug builds.

Panics

If it is Ok and debug_assertions are enabled, the method panics. If debug_assertions are disabled, the method is a no-op even if it is Ok.

Examples

use chain_assertions::prelude::*;

let x: Result<&str, i32> = Err(42);
let _ = x.debug_assert_err();

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<T, E> AssertErrExt for Result<T, E>

where T: Debug,

fn assert_err(self) -> Self

fn debug_assert_err(self) -> Self

Implementors