code: Iterator<Row> data(IteratorType type) {
      Iterator<Row> itr;
      switch(type) {
        case OLD_DATA_EXPECTED:
          itr = oldData.getRows().iterator();
          break;
        case NEW_DATA_EXPECTED:
          itr = newData.getRows().iterator();
          break;
        case OLD_DATA_ERRORS_EXPECTED:
          itr = oldDataMatch.deleted();
          break;
        case OLD_DATA_ERRORS_ACTUAL:
          itr = oldDataMatch.inserted();
          break;
        case NEW_DATA_ERRORS_EXPECTED:
          itr = newDataMatch.deleted();
          break;
        case NEW_DATA_ERRORS_ACTUAL:
          itr = newDataMatch.inserted();
          break;
        default:
          throw new InternalErrorException("Unexpected case!");      
      }
      return itr;
    }
docs: Get information for the assertion.
  @param type Type of iterator
  @return An iterator for the specified data.