ConfirmSocketSetOptionOnResetConnections may have a race in it wherein an ASIO socket's connect() call may not return by the time the ASIO acceptor on the server end returns from accept(). In ConfirmSocketSetOptionOnResetConnections, this allows the server side to close the connection before connect() finishes, which causes connect() to fail and throw, failing the test. Add a synchronization mechanism to ensure that the onAccept() callback associated with the acceptor doesn't run until connect() has fully completed.