Macro conn_try 

macro_rules! conn_try {
    ($expr:expr, $conn:expr $(,)?) => { ... };
}

Unwraps an Result::Ok or returns the Conn with a 500 status.

use trillium::{Conn, conn_try};
use trillium_testing::TestServer;

let handler = |mut conn: Conn| async move {
    let request_body_string = conn_try!(conn.request_body_string().await, conn);
    let u8: u8 = conn_try!(request_body_string.parse(), conn);
    conn.ok(format!("received u8 as body: {}", u8))
};

let app = TestServer::new(handler).await;
app.post("/").with_body("not u8").await.assert_status(500);
app.post("/")
    .with_body("10")
    .await
    .assert_ok()
    .assert_body("received u8 as body: 10");