Method NumBatches

cpp/src/arrow/dataset/scanner_test.cc:199–199

    return util::TotalBufferSize(*scan_tasks_[batch_number].batch);
  }
  int NumBatches() override { return static_cast<int>(scan_tasks_.size()); }

  // ### Unit Test API ###
  void DeliverBatches(bool slow, const std::vector<MockScanTask>& to_deliver) {