checkers

Checkers is a simple allocation checker for Rust. It plugs in through the global allocator API and can sanity check your unsafe Rust during integration testing.

It can check for the following things:

• Double-frees.
• Attempts to free regions which are not allocated.
• Attempts to free only part of regions which are allocated.
• Attempts to free a region with a mismatching layout.
• Underlying allocator producting regions not adhering to the requested layout. Namely size and alignment.
• Other arbitrary user-defined conditions (see test).

What it can't do:

• Test multithreaded code. Since the allocator is global, it is difficult to scope the state for each test case.

Examples

You use checkers by installing checkers::Allocator as your allocator, then making use of either the #[checkers::test] macro or the checkers::with function.

#[global_allocator]
static ALLOCATOR: checkers::Allocator = checkers::Allocator;

#[checkers::test]
fn test_allocations() {
    let _ = Box::into_raw(Box::new(42));
}

The above would result in the following test output:

dangling region: 0x226e5784f30-0x226e5784f40 (size: 16, align: 8).
thread 'test_leak_box' panicked at 'allocation checks failed', tests\leaky_tests.rs:4:1

With checkers::with, we can perform more detailed diagnostics:

#[global_allocator]
static ALLOCATOR: checkers::Allocator = checkers::Allocator;

let snapshot = checkers::with(|| {
    let _ = vec![1, 2, 3, 4];
});

assert_eq!(2, snapshot.events.len());
assert!(snapshot.events[0].is_allocation_with(|r| r.size >= 16));
assert!(snapshot.events[1].is_deallocation_with(|a| a.size >= 16));
assert_eq!(1, snapshot.events.allocations());
assert_eq!(1, snapshot.events.deallocations());
assert!(snapshot.events.max_memory_used().unwrap() >= 16);