Function GetEmptySegmentKeyOutput

cpp/src/arrow/acero/hash_aggregate_test.cc:5300–5307

extracts the expected output for one segment

// extracts the expected output for one segment
Result<std::shared_ptr<Array>> GetEmptySegmentKeyOutput() {
  ARROW_ASSIGN_OR_RAISE(auto chunked, GetSingleSegmentKeyOutput());
  ARROW_ASSIGN_OR_RAISE(auto table, Table::FromChunkedStructArray(chunked));
  ARROW_ASSIGN_OR_RAISE(auto removed, table->RemoveColumn(0));
  auto sliced = removed->Slice(0, 4);
  ARROW_ASSIGN_OR_RAISE(auto batch, sliced->CombineChunksToBatch());
  return batch->ToStructArray();
}

void TestEmptySegmentKey(GroupByFunction group_by,
                         std::function<Result<std::shared_ptr<Table>>()> get_table) {