waynexia commented on code in PR #16856:
URL: https://github.com/apache/datafusion/pull/16856#discussion_r2226354689
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datafusion/functions/src/string/chr.rs:
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@@ -132,3 +134,79 @@ impl ScalarUDFImpl for ChrFunc {
self.doc()
}
}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use arrow::array::{Array, Int64Array, StringArray};
+ use datafusion_common::assert_contains;
+
+ #[test]
+ fn test_chr_normal() {
+ let input = Arc::new(Int64Array::from(vec![
+ Some(65), // A
+ Some(66), // B
+ Some(67), // C
+ Some(128640), // 🚀
+ Some(8364), // €
+ Some(945), // α
+ None, // NULL
+ Some(32), // space
+ Some(10), // newline
+ Some(9), // tab
+ ]));
+ let result = chr(&[input]).unwrap();
+ let string_array =
result.as_any().downcast_ref::<StringArray>().unwrap();
+ let expected = ["A", "B", "C", "🚀", "€", "α", "", " ", "\n", "\t"];
+
+ assert_eq!(string_array.len(), 10);
+ for (i, e) in expected.iter().enumerate() {
+ assert_eq!(string_array.value(i), *e);
+ }
+ }
+
+ #[test]
+ fn test_chr_error() {
+ // chr(0) returns an error
+ let input = Arc::new(Int64Array::from(vec![0]));
+ let result = chr(&[input]);
+ assert!(result.is_err());
+ assert_contains!(
+ result.err().unwrap().to_string(),
+ "null character not permitted"
+ );
+
+ // invalid Unicode code points (too large)
+ let input = Arc::new(Int64Array::from(vec![i64::MAX]));
+ let result = chr(&[input]);
+ assert!(result.is_err());
+ assert_contains!(
+ result.err().unwrap().to_string(),
+ "requested character too large for encoding"
+ );
+
+ // negative input
+ let input = Arc::new(Int64Array::from(vec![i64::MIN + 2i64])); // will
be 2 if cast to u32
Review Comment:
Cast in Rust. Input out of the valid UTF-8 range will report an error, but
input like `i64::MIN + 2i64` will be first cast to `2u32` and then become a
valid UTF-8 char, which IMO is invalid. So I add a negative checker to make
sure this won't happen.
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