Add test for Printer Json format with statistics

Author: raulcd

cpp/src/parquet/metadata.cc

@@ -92,6 +92,14 @@ std::string ParquetVersionToString(ParquetVersion::type ver) {
 template <typename DType>
 static std::shared_ptr<Statistics> MakeTypedColumnStats(
     const format::ColumnMetaData& metadata, const ColumnDescriptor* descr) {
+  std::optional<bool> min_exact =
+      metadata.statistics.__isset.is_min_value_exact
+          ? std::optional<bool>(metadata.statistics.is_min_value_exact)
+          : std::nullopt;
+  std::optional<bool> max_exact =
+      metadata.statistics.__isset.is_max_value_exact
+          ? std::optional<bool>(metadata.statistics.is_max_value_exact)
+          : std::nullopt;
   // If ColumnOrder is defined, return max_value and min_value
   if (descr->column_order().get_order() == ColumnOrder::TYPE_DEFINED_ORDER) {
     return MakeStatistics<DType>(
@@ -100,9 +108,7 @@ static std::shared_ptr<Statistics> MakeTypedColumnStats(
         metadata.statistics.null_count, metadata.statistics.distinct_count,
         metadata.statistics.__isset.max_value && metadata.statistics.__isset.min_value,
         metadata.statistics.__isset.null_count,
-        metadata.statistics.__isset.distinct_count,
-        metadata.statistics.__isset.is_min_value_exact,
-        metadata.statistics.__isset.is_max_value_exact);
+        metadata.statistics.__isset.distinct_count, min_exact, max_exact);
   }
   // Default behavior
   return MakeStatistics<DType>(
@@ -111,8 +117,7 @@ static std::shared_ptr<Statistics> MakeTypedColumnStats(
       metadata.statistics.null_count, metadata.statistics.distinct_count,
       metadata.statistics.__isset.max && metadata.statistics.__isset.min,
       metadata.statistics.__isset.null_count, metadata.statistics.__isset.distinct_count,
-      metadata.statistics.__isset.is_min_value_exact,
-      metadata.statistics.__isset.is_max_value_exact);
+      min_exact, max_exact);
 }
 
 namespace {

cpp/src/parquet/printer.cc

@@ -353,15 +353,15 @@ void ParquetFilePrinter::JSONPrint(std::ostream& stream, std::list<int> selected
           if (stats->is_max_value_exact().has_value()) {
             stream << ", "
                    << R"("IsMaxValueExact": ")"
-                   << (stats->is_max_value_exact().value() ? "true" : "false") << "\"";
+                   << (stats->is_max_value_exact().value() ? "True" : "False") << "\"";
           } else {
             stream << ", "
                    << R"("IsMaxValueExact": "unknown")";
           }
           if (stats->is_min_value_exact().has_value()) {
             stream << ", "
                    << R"("IsMinValueExact": ")"
-                   << (stats->is_min_value_exact().value() ? "true" : "false") << "\"";
+                   << (stats->is_min_value_exact().value() ? "True" : "False") << "\"";
           } else {
             stream << ", "
                    << R"("IsMinValueExact": "unknown")";

cpp/src/parquet/reader_test.cc

@@ -1108,6 +1108,37 @@ class TestJSONWithLocalFile : public ::testing::Test {
   }
 };
 
+TEST_F(TestJSONWithLocalFile, JSONOutputWithStatistics) {
+  std::string json_output = R"###({
+  "FileName": "nested_lists.snappy.parquet",
+  "Version": "1.0",
+  "CreatedBy": "parquet-mr version 1.8.2 (build c6522788629e590a53eb79874b95f6c3ff11f16c)",
+  "TotalRows": "3",
+  "NumberOfRowGroups": "1",
+  "NumberOfRealColumns": "2",
+  "NumberOfColumns": "2",
+  "Columns": [
+     { "Id": "0", "Name": "a.list.element.list.element.list.element", "PhysicalType": "BYTE_ARRAY", "ConvertedType": "UTF8", "LogicalType": {"Type": "String"} },
+     { "Id": "1", "Name": "b", "PhysicalType": "INT32", "ConvertedType": "NONE", "LogicalType": {"Type": "None"} }
+  ],
+  "RowGroups": [
+     {
+       "Id": "0",  "TotalBytes": "155",  "TotalCompressedBytes": "0",  "Rows": "3",
+       "ColumnChunks": [
+          {"Id": "0", "Values": "18", "StatsSet": "False",
+           "Compression": "SNAPPY", "Encodings": "PLAIN_DICTIONARY(DICT_PAGE) PLAIN_DICTIONARY", "UncompressedSize": "103", "CompressedSize": "104" },
+          {"Id": "1", "Values": "3", "StatsSet": "True", "Stats": {"NumNulls": "0", "Max": "1", "Min": "1", "IsMaxValueExact": "unknown", "IsMinValueExact": "unknown" },
+           "Compression": "SNAPPY", "Encodings": "PLAIN_DICTIONARY(DICT_PAGE) PLAIN_DICTIONARY", "UncompressedSize": "52", "CompressedSize": "56" }
+        ]
+     }
+  ]
+}
+)###";
+
+  std::string json_content = ReadFromLocalFile("nested_lists.snappy.parquet");
+  ASSERT_EQ(json_output, json_content);
+}
+
 TEST_F(TestJSONWithLocalFile, JSONOutput) {
   std::string json_output = R"###({
   "FileName": "alltypes_plain.parquet",