mem_dbg 0.4.3

Traits and associated procedural macros to display recursively the layout and memory usage of a value
Documentation 
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//! Test to ensure MutexGuard is handled correctly.
#![cfg(all(feature = "std", feature = "derive"))]

use mem_dbg::*;
use std::sync::{Mutex, MutexGuard};

#[test]
/// Test mem_size on a struct containing a MutexGuard.
fn test_mutex_guard() {
    #[derive(MemSize)]
    struct Test<'a> {
        guard: MutexGuard<'a, i32>,
    }

    let mutex_source = Mutex::new(0);

    let s = Test {
        guard: mutex_source.lock().unwrap(),
    };
    let size = s.mem_size(SizeFlags::default());
    let size_of_usize = core::mem::size_of::<usize>();

    assert_eq!(
        size,
        2 * size_of_usize,
        "A MutexGuard is two pointers in size"
    );
}

#[test]
fn test_mutex_guard_follow_refs_counts_target_header() {
    let mutex_source = Mutex::new(vec![1_u8, 2, 3]);
    let guard = mutex_source.lock().unwrap();

    assert_eq!(
        guard.mem_size(SizeFlags::FOLLOW_REFS),
        core::mem::size_of_val(&guard) + core::mem::size_of::<Vec<u8>>() + 3
    );
}

#[test]
fn test_mutex_guard_follow_refs_marks_reference() {
    let mutex_source = Mutex::new(vec![1_u8, 2, 3]);
    let guard = mutex_source.lock().unwrap();
    let mut output = String::new();

    guard
        .mem_dbg_on(&mut output, DbgFlags::FOLLOW_REFS)
        .expect("mem_dbg_on");

    assert!(output.contains("@ 0x"));
}