should be it

external/duckdb/test/appender/test_nested_appender.cpp

@@ -0,0 +1,59 @@
+#include "catch.hpp"
+#include "duckdb/main/appender.hpp"
+#include "test_helpers.hpp"
+
+#include <vector>
+
+using namespace duckdb;
+using namespace std;
+
+TEST_CASE("Test appender with lists", "[appender]") {
+	duckdb::unique_ptr<QueryResult> result;
+	DuckDB db(nullptr);
+	Connection con(db);
+
+	REQUIRE_NO_FAIL(con.Query("CREATE TABLE lists(i INTEGER[])"));
+
+	// append a value to the table
+	Appender appender(con, "lists");
+
+	auto list_value = Value::LIST(LogicalType::INTEGER, {Value::INTEGER(3)});
+	auto empty_list_value = Value::LIST(LogicalType::INTEGER, duckdb::vector<Value>());
+
+	appender.AppendRow(list_value);
+	appender.AppendRow(empty_list_value);
+
+	appender.Close();
+
+	// we can select the value now
+	result = con.Query("SELECT * FROM lists");
+	REQUIRE(CHECK_COLUMN(result, 0, {list_value, empty_list_value}));
+}
+
+TEST_CASE("Test appender with nested lists", "[appender]") {
+	duckdb::unique_ptr<QueryResult> result;
+	DuckDB db(nullptr);
+	Connection con(db);
+
+	REQUIRE_NO_FAIL(con.Query("CREATE TABLE lists(i INTEGER[][])"));
+
+	// append a value to the table
+	Appender appender(con, "lists");
+
+	auto int_list_type = LogicalType::LIST(LogicalType::INTEGER);
+	auto nested_int_list_type = LogicalType::LIST(int_list_type);
+	auto list_value =
+	    Value::LIST(int_list_type, {Value::LIST(LogicalType::INTEGER, {Value::INTEGER(1)}),
+	                                Value::LIST(LogicalType::INTEGER, {Value::INTEGER(2), Value::INTEGER(3)})});
+	auto empty_list_value = Value::LIST(int_list_type, duckdb::vector<Value>());
+	auto null_list_value = Value(nested_int_list_type);
+	appender.AppendRow(list_value);
+	appender.AppendRow(empty_list_value);
+	appender.AppendRow(null_list_value);
+
+	appender.Close();
+
+	// we can select the value now
+	result = con.Query("SELECT * FROM lists");
+	REQUIRE(CHECK_COLUMN(result, 0, {list_value, empty_list_value, null_list_value}));
+}