Function expect_empty

test/exec/async_scope/test_spawn_future.cpp:18–31

namespace
{
  void expect_empty(exec::async_scope& scope)
  {
    ex::run_loop       loop;
    ex::scheduler auto sch = loop.get_scheduler();
    CHECK_FALSE(ex::execute_may_block_caller(sch));
    auto op = ex::connect(ex::then(scope.on_empty(),
                                   [&]()
                                   {
                                     loop.finish();
    }),
                          expect_void_receiver{ex::prop{ex::get_scheduler, sch}});
    ex::start(op);
    loop.run();
  }

#if !STDEXEC_NO_STDCPP_EXCEPTIONS()
  //! Sender that throws exception when connected