Function init_async 

pub fn init_async() -> (Runtime, impl Drop)

Initialize globals for tests that need a separate Tokio runtime instance.

This is generally used in proptests, which don’t support the #[tokio::test] attribute.

If a runtime needs to be shared between tests, use the SINGLE_THREADED_RUNTIME or MULTI_THREADED_RUNTIME instances instead.

See also the init function, which is called by this function.