Hi,

I don't do rust myself, so I cannot tell. That test uses a macro, and this specific test is only closing the instance, without calling any other method (afaict...).

My solution doesn't rely on recusion, but after passing some tests (somewhere between 37 and 54) it panics with

thread 'tests::failure::properties_and_methods_vs_locking::unlocked_only_close' has overflowed its stack
fatal runtime error: stack overflow


Caused by:
  process didn't exit successfully: `/workspace/target/debug/deps/challenge-07bd72047d917620 --show-output -Z unstable-options --format json` (signal: 6, SIGABRT: process abort signal)

Any idea why?