Function test_make_map_with_null_maps

datafusion/functions-nested/src/map.rs:676–736

()

    use super::*;
    #[test]
    fn test_make_map_with_null_maps() {
        // Test that NULL map values (entire map is NULL) are correctly handled
        // This test directly calls make_map_batch with a List containing NULL elements
        //
        // Background: On main branch, the code would fail with "map key cannot be null"
        // because it couldn't distinguish between:
        // - NULL map (entire map is NULL) - should be allowed
        // - null key within a map - should be rejected

        // Build keys array: [['a'], NULL, ['b']]
        // The middle NULL represents an entire NULL map, not a null key
        let mut key_builder =
            arrow::array::ListBuilder::new(arrow::array::StringBuilder::new());

        // First map: ['a']
        key_builder.values().append_value("a");
        key_builder.append(true);

        // Second map: NULL (entire map is NULL)
        key_builder.append(false);

        // Third map: ['b']
        key_builder.values().append_value("b");
        key_builder.append(true);

        let keys_array = Arc::new(key_builder.finish());

        // Build values array: [[1], [2], [3]]
        let mut value_builder =
            arrow::array::ListBuilder::new(arrow::array::Int32Builder::new());

        value_builder.values().append_value(1);
        value_builder.append(true);

        value_builder.values().append_value(2);
        value_builder.append(true);

        value_builder.values().append_value(3);
        value_builder.append(true);

        let values_array = Arc::new(value_builder.finish());

        // Call make_map_batch - should succeed
        let result = make_map_batch(&[
            ColumnarValue::Array(keys_array),
            ColumnarValue::Array(values_array),
        ]);

        assert!(result.is_ok(), "Should handle NULL maps correctly");

        // Verify the result
        let map_array = match result.unwrap() {
            ColumnarValue::Array(arr) => arr,
            _ => panic!("Expected Array result"),
        };

        assert_eq!(map_array.len(), 3, "Should have 3 maps");
        assert!(!map_array.is_null(0), "First map should not be NULL");