refactoring; improve round-trip tests
refactoring; improve round-trip tests

cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless,cyber-dojo/runner,cyber-dojo/runner,cyber-dojo/runner_stateless,cyber-dojo/runner_stateless