fix(inspect): address remaining PR review comments

Author: WZhuo

src/iceberg/inspect/snapshots_table.cc

@@ -23,15 +23,14 @@
 #include <cstddef>
 #include <memory>
 #include <optional>
-#include <tuple>
 #include <utility>
 #include <vector>
 
 #include <nanoarrow/nanoarrow.h>
 
-#include "iceberg/arrow/nanoarrow_status_internal.h"
 #include "iceberg/arrow_c_data_util_internal.h"
 #include "iceberg/arrow_row_builder_internal.h"
+#include "iceberg/nanoarrow_status_internal.h"
 #include "iceberg/schema.h"
 #include "iceberg/schema_field.h"
 #include "iceberg/schema_internal.h"
@@ -66,12 +65,16 @@ Status AppendSnapshot(ArrowRowBuilder& builder, const Snapshot& snapshot) {
 
   ICEBERG_RETURN_UNEXPECTED(AppendString(builder.column(4), snapshot.manifest_list));
 
-  auto summary = snapshot.summary;
-  summary.erase(SnapshotSummaryFields::kOperation);
-  if (summary.empty()) {
-    ICEBERG_RETURN_UNEXPECTED(AppendNull(builder.column(5)));
+  if (!snapshot.summary.empty()) {
+    if (snapshot.summary.contains(SnapshotSummaryFields::kOperation)) {
+      auto summary = snapshot.summary;
+      summary.erase(SnapshotSummaryFields::kOperation);
+      ICEBERG_RETURN_UNEXPECTED(AppendStringMap(builder.column(5), summary));
+    } else {
+      ICEBERG_RETURN_UNEXPECTED(AppendStringMap(builder.column(5), snapshot.summary));
+    }
   } else {
-    ICEBERG_RETURN_UNEXPECTED(AppendStringMap(builder.column(5), summary));
+    ICEBERG_RETURN_UNEXPECTED(AppendNull(builder.column(5)));
   }
 
   return builder.FinishRow();
@@ -87,7 +90,7 @@ class SnapshotsTableStream {
         new SnapshotsTableStream(std::move(metadata), std::move(arrow_schema)));
   }
 
-  ~SnapshotsTableStream() { std::ignore = Close(); }
+  ~SnapshotsTableStream() = default;
 
   Status Close() {
     metadata_.reset();

src/iceberg/test/metadata_table_test_base.h

@@ -85,9 +85,11 @@ class MetadataTableTestBase : public ::testing::Test {
       ArrowArrayStream&& stream) {
     auto reader_result = ::arrow::ImportRecordBatchReader(&stream);
     if (!reader_result.ok()) {
+      if (stream.release != nullptr) {
+        stream.release(&stream);
+      }
       return InvalidArrowData(reader_result.status().ToString());
     }
-
     auto batches_result = reader_result.ValueUnsafe()->ToRecordBatches();
     if (!batches_result.ok()) {
       return InvalidArrowData(batches_result.status().ToString());

src/iceberg/test/snapshots_table_test.cc

@@ -88,8 +88,8 @@ TEST_F(SnapshotsTableTest, Scan) {
 
   // Column 0: committed_at (timestamptz) — microseconds since epoch.
   auto committed_at = std::static_pointer_cast<::arrow::TimestampArray>(batch->column(0));
-  EXPECT_EQ(committed_at->Value(0), 1234567890000 * 1000);
-  EXPECT_EQ(committed_at->Value(1), 9876543210000 * 1000);
+  EXPECT_EQ(committed_at->Value(0), 1234567890000LL * 1000);
+  EXPECT_EQ(committed_at->Value(1), 9876543210000LL * 1000);
 
   // Column 1: snapshot_id (long) — returned in storage order.
   auto snapshot_ids = std::static_pointer_cast<::arrow::Int64Array>(batch->column(1));
@@ -159,7 +159,7 @@ TEST_F(SnapshotsTableTest, ScanSkipsNullSnapshots) {
   EXPECT_EQ(batches.front()->num_rows(), 2);
 }
 
-TEST_F(SnapshotsTableTest, ScanTreatsEmptySummaryAsNull) {
+TEST_F(SnapshotsTableTest, ScanEmptySummary) {
   auto [missing_summary, operation_only_summary] = MakeTestSnapshots();
   missing_summary->summary.clear();
   operation_only_summary->summary = {
@@ -176,7 +176,8 @@ TEST_F(SnapshotsTableTest, ScanTreatsEmptySummaryAsNull) {
   auto summaries =
       std::static_pointer_cast<::arrow::MapArray>(batches.front()->column(5));
   EXPECT_TRUE(summaries->IsNull(0));
-  EXPECT_TRUE(summaries->IsNull(1));
+  EXPECT_FALSE(summaries->IsNull(1));
+  EXPECT_EQ(summaries->value_length(1), 0);
 }
 
 TEST_F(SnapshotsTableTest, ScanReturnsMultipleBatches) {