Macro assert_unreachable 

macro_rules! assert_unreachable {
    ($message:expr$(, $details:expr)?) => { ... };
    ($($rest:tt)*) => { ... };
}

Assert that a line of code is never reached. The corresponding test property will fail if this macro is ever called. (If it is never called the test property will therefore pass.) This test property will be viewable in the Antithesis SDK: Reachablity assertions group.

Example

use serde::Serialize;
use antithesis_sdk::{assert_unreachable, random};

// Only serialized when the assertion emits; see assert_always.
#[derive(Serialize)]
struct Details { max_allowed: u64, actual: u64 }

const MAX_ALLOWED: u64 = 100;
let actual = random::get_random() % 120u64;
let details = Details { max_allowed: MAX_ALLOWED, actual };
if (actual > 120u64) {
    antithesis_sdk::assert_unreachable!("Value is above range", &details);
}