Method SetUp

cpp/src/arrow/dataset/dataset_test.cc:521–805

  using PathAndContent = std::vector<std::pair<std::string, std::string>>;

  void SetUp() override {
    // The following test creates 2 sources with divergent but compatible
    // schemas. Each source have a common partitioning where the
    // fields are not materialized in the data fragments.
    //
    // Each data is composed of 2 data fragments with divergent but
    // compatible schemas. The data fragment within a source share at
    // least one column.
    //
    // Thus, the fixture helps verifying various scenarios where the Scanner
    // must fix the RecordBatches to align with the final unified schema exposed
    // to the consumer.
    static constexpr auto ds1_df1 = "/dataset/alpha/part_ds=1/part_df=1/data.json";
    static constexpr auto ds1_df2 = "/dataset/alpha/part_ds=1/part_df=2/data.json";
    static constexpr auto ds2_df1 = "/dataset/beta/part_ds=2/part_df=1/data.json";
    static constexpr auto ds2_df2 = "/dataset/beta/part_ds=2/part_df=2/data.json";
    auto files = PathAndContent{
        // First Dataset
        {ds1_df1, R"([{"phy_1": 111, "phy_2": 211}])"},
        {ds1_df2, R"([{"phy_2": 212, "phy_3": 312}])"},
        // Second Dataset
        {ds2_df1, R"([{"phy_3": 321, "phy_4": 421}])"},
        {ds2_df2, R"([{"phy_4": 422, "phy_2": 222}])"},
    };

    auto mock_fs = std::make_shared<fs::internal::MockFileSystem>(fs::kNoTime);
    for (const auto& f : files) {
      ARROW_EXPECT_OK(mock_fs->CreateFile(f.first, f.second, /* recursive */ true));
    }
    fs_ = mock_fs;

    auto get_source =
        [this](std::string base,
               std::vector<std::string> paths) -> Result<std::shared_ptr<Dataset>> {
      auto resolver = [](const FileSource& source) -> std::shared_ptr<Schema> {
        auto path = source.path();
        // A different schema for each data fragment.
        if (path == ds1_df1) {
          return SchemaFromNames({"phy_1", "phy_2"});
        } else if (path == ds1_df2) {
          return SchemaFromNames({"phy_2", "phy_3"});
        } else if (path == ds2_df1) {
          return SchemaFromNames({"phy_3", "phy_4"});
        } else if (path == ds2_df2) {
          return SchemaFromNames({"phy_4", "phy_2"});
        }

        return nullptr;
      };

      auto format = std::make_shared<JSONRecordBatchFileFormat>(resolver);

      FileSystemFactoryOptions options;
      options.partition_base_dir = base;
      options.partitioning =
          std::make_shared<HivePartitioning>(SchemaFromNames({"part_ds", "part_df"}));

      ARROW_ASSIGN_OR_RAISE(auto factory,