refactoring; update tests (working towards common set of tests for all runners)
refactoring; update tests (working towards common set of tests for all runners)

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