function getCommandsFlat( groups ) {
  return Object.values( groups ).reduce( ( carry, group ) => {
    const commands = Object.values( group.tests ).reduce( ( carry, test ) => {
      return carry.concat( Object.values( test.commands ) );
    }, []);
    return carry.concat( commands );
  }, []);
}
@param {object} ref = { testId, groupId, id }
@returns {object}