I find myself using debug_here (https://github.com/ethanpailes/debug-here) which does similar things but for desktop-class debugging. It hasn't been updated in a while, but it still works for me on Windows at least.
Due to reliance on core_intrinsics it is necessary to develop using nightly Rust, but there are stubs in place so a production build will not require nightly.
I recently released version 0.2 which includes no_std support and adds optional log message arguments to the ensure macro.