From 2c24d6375c13ae27306ebdbff7eacb5572976bf8 Mon Sep 17 00:00:00 2001
From: Hung <hung@Hungs-Mac-mini.local>
Date: Fri, 11 Sep 2026 01:22:58 +0800
Subject: [PATCH] test: cover slice over expression-produced non-null element
 arrays (#5743)

---
 .../spark-expr/src/array_funcs/array_slice.rs | 21 ++++++++++++++++++-
 .../comet/CometArrayExpressionSuite.scala     | 17 +++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/native/spark-expr/src/array_funcs/array_slice.rs b/native/spark-expr/src/array_funcs/array_slice.rs
index fcd3b467a6c..28e1fc51857 100644
--- a/native/spark-expr/src/array_funcs/array_slice.rs
+++ b/native/spark-expr/src/array_funcs/array_slice.rs
@@ -188,6 +188,14 @@ mod tests {
     use arrow::datatypes::{Field, Int32Type};
 
     fn build_list(rows: Vec<Option<Vec<Option<i32>>>>) -> Arc<ListArray> {
+        let field = Arc::new(Field::new("item", DataType::Int32, true));
+        build_list_with_field(field, rows)
+    }
+
+    fn build_list_with_field(
+        field: FieldRef,
+        rows: Vec<Option<Vec<Option<i32>>>>,
+    ) -> Arc<ListArray> {
         let mut offsets = vec![0i32];
         let mut values: Vec<Option<i32>> = Vec::new();
         let mut nulls = NullBufferBuilder::new(rows.len());
@@ -202,7 +210,6 @@ mod tests {
             offsets.push(values.len() as i32);
         }
         let values = Arc::new(Int32Array::from(values)) as ArrayRef;
-        let field = Arc::new(Field::new("item", DataType::Int32, true));
         Arc::new(ListArray::new(
             field,
             OffsetBuffer::new(offsets.into()),
@@ -371,4 +378,16 @@ mod tests {
         let length = Int64Array::from(vec![Some(-1)]);
         assert!(slice_list::<i32>(list.as_ref(), &start, &length).is_err());
     }
+
+    #[test]
+    fn preserves_non_nullable_element_field() {
+        let mut metadata = std::collections::HashMap::new();
+        metadata.insert("spark.element".to_string(), "non-null".to_string());
+        let field = Arc::new(Field::new("element", DataType::Int32, false).with_metadata(metadata));
+        let list = build_list_with_field(field, vec![Some(vec![Some(1), Some(2), Some(3)])]);
+        let start = Int64Array::from(vec![Some(1)]);
+        let length = Int64Array::from(vec![Some(2)]);
+        let result = slice_list::<i32>(list.as_ref(), &start, &length).unwrap();
+        assert_eq!(result.data_type(), list.data_type());
+    }
 }
diff --git a/spark/src/test/scala/org/apache/comet/CometArrayExpressionSuite.scala b/spark/src/test/scala/org/apache/comet/CometArrayExpressionSuite.scala
index ad86dd15bc1..8d0a04d7d67 100644
--- a/spark/src/test/scala/org/apache/comet/CometArrayExpressionSuite.scala
+++ b/spark/src/test/scala/org/apache/comet/CometArrayExpressionSuite.scala
@@ -1489,6 +1489,23 @@ class CometArrayExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelp
     }
   }
 
+  // Spark declares split and sequence as ArrayType(..., containsNull=false). Native
+  // Parquet already normalizes stored children to nullable, so the non-null element
+  // field is produced after the scan. CometSlice must infer its return type from that
+  // input field; a planned nullable element disagrees with the kernel and crashes.
+  // https://github.com/apache/datafusion-comet/issues/5743
+  test("slice over expression-produced non-null element arrays (#5743)") {
+    val input = Seq((1, "axb", 2), (2, "", 3), (3, "cxd", 2))
+    withParquetDataFrame(input) { parquet =>
+      withParquetTable(parquet.toDF("id", "s", "n"), "t") {
+        checkSparkAnswerAndOperator(sql("SELECT id, slice(split(s, 'x'), 1, n) AS a FROM t"))
+        checkSparkAnswerAndOperator(sql("SELECT id, slice(sequence(1, n), 1, 2) AS a FROM t"))
+        checkSparkAnswerAndOperator(
+          sql("SELECT id, slice(concat(split(s, 'x'), array('z')), 1, n) AS a FROM t"))
+      }
+    }
+  }
+
   // https://issues.apache.org/jira/browse/SPARK-55747
   test("(ansi) GetArrayItem on null array from split()") {
     withSQLConf(