Trait AssertNoneExt

pub trait AssertNoneExt {
    // Required methods
    fn assert_none(self) -> Self;
    fn debug_assert_none(self) -> Self;
}

Expand description

An extension trait to add the assertion_none methods.

Required Methods§

Asserts the Option is None.

If it is Some, the method panics.

use chain_assertions::prelude::*;

let x: Option<i32> = None;
let x = x.assert_none().map(|x| x * 2);
assert_eq!(x, None);

use chain_assertions::prelude::*;

let x: Option<i32> = Some(21);
let _ = x.assert_none().map(|x| x * 2);
//        ^-- panics here

Asserts the Option is None only in debug builds.

The method panics if all following conditions are satisfied:

Otherwise, the method returns self as is.

use chain_assertions::prelude::*;

let x: Option<i32> = None;
let x = x.debug_assert_none().map(|v| v * 2);
assert_eq!(x, None);

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".