From 200508b6eb8d8b7f21ff1a8beb095d9631615dba Mon Sep 17 00:00:00 2001
From: Andrew Lamb <andrew@nerdnetworks.org>
Date: Fri, 2 Feb 2024 10:20:02 -0500
Subject: [PATCH] wire in and add a test

---
 datafusion/core/src/lib.rs                    |  6 ++++
 datafusion/core/src/prelude.rs                |  2 ++
 .../tests/dataframe/dataframe_functions.rs    | 30 ++++++++++++++++++-
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/datafusion/core/src/lib.rs b/datafusion/core/src/lib.rs
index 0f7292e1c3d31..d78d7a38a1c34 100644
--- a/datafusion/core/src/lib.rs
+++ b/datafusion/core/src/lib.rs
@@ -521,6 +521,12 @@ pub mod functions {
     pub use datafusion_functions::*;
 }
 
+/// re-export of [`datafusion_functions_array`] crate, if "array_expressions" feature is enabled
+pub mod functions_array {
+    #[cfg(feature = "array_expressions")]
+    pub use datafusion_functions::*;
+}
+
 #[cfg(test)]
 pub mod test;
 pub mod test_util;
diff --git a/datafusion/core/src/prelude.rs b/datafusion/core/src/prelude.rs
index 69c33355402bf..d82a5a2cc1a11 100644
--- a/datafusion/core/src/prelude.rs
+++ b/datafusion/core/src/prelude.rs
@@ -39,6 +39,8 @@ pub use datafusion_expr::{
     Expr,
 };
 pub use datafusion_functions::expr_fn::*;
+#[cfg(feature = "array_expressions")]
+pub use datafusion_functions_array::expr_fn::*;
 
 pub use std::ops::Not;
 pub use std::ops::{Add, Div, Mul, Neg, Rem, Sub};
diff --git a/datafusion/core/tests/dataframe/dataframe_functions.rs b/datafusion/core/tests/dataframe/dataframe_functions.rs
index 486ea712edeb7..48b9120698adb 100644
--- a/datafusion/core/tests/dataframe/dataframe_functions.rs
+++ b/datafusion/core/tests/dataframe/dataframe_functions.rs
@@ -20,6 +20,8 @@ use arrow::{
     array::{Int32Array, StringArray},
     record_batch::RecordBatch,
 };
+use arrow_array::types::Int32Type;
+use arrow_array::ListArray;
 use arrow_schema::SchemaRef;
 use std::sync::Arc;
 
@@ -40,6 +42,7 @@ fn test_schema() -> SchemaRef {
     Arc::new(Schema::new(vec![
         Field::new("a", DataType::Utf8, false),
         Field::new("b", DataType::Int32, false),
+        Field::new("l", DataType::new_list(DataType::Int32, true), true),
     ]))
 }
 
@@ -57,6 +60,12 @@ async fn create_test_table() -> Result<DataFrame> {
                 "123AbcDef",
             ])),
             Arc::new(Int32Array::from(vec![1, 10, 10, 100])),
+            Arc::new(ListArray::from_iter_primitive::<Int32Type, _, _>(vec![
+                Some(vec![Some(0), Some(1), Some(2)]),
+                None,
+                Some(vec![Some(3), None, Some(5)]),
+                Some(vec![Some(6), Some(7)]),
+            ])),
         ],
     )?;
 
@@ -67,7 +76,7 @@ async fn create_test_table() -> Result<DataFrame> {
     ctx.table("test").await
 }
 
-/// Excutes an expression on the test dataframe as a select.
+/// Executes an expression on the test dataframe as a select.
 /// Compares formatted output of a record batch with an expected
 /// vector of strings, using the assert_batch_eq! macro
 macro_rules! assert_fn_batches {
@@ -841,3 +850,22 @@ async fn test_fn_decode() -> Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+async fn test_fn_array_to_string() -> Result<()> {
+    let expr = array_to_string(col("l"), lit("***"));
+
+    let expected = [
+        "+-------------------------------------+",
+        "| array_to_string(test.l,Utf8(\"***\")) |",
+        "+-------------------------------------+",
+        "| 0***1***2                           |",
+        "|                                     |",
+        "| 3***5                               |",
+        "| 6***7                               |",
+        "+-------------------------------------+",
+    ];
+    assert_fn_batches!(expr, expected);
+
+    Ok(())
+}