From 54403cf2b6d8df367aa511ba113c70ed3f4ed18d Mon Sep 17 00:00:00 2001
From: Hussenet Thomas <113238884+LeJamon@users.noreply.github.com>
Date: Sat, 30 May 2026 15:38:25 +0200
Subject: [PATCH] fix(#166): preserve Utf8Error detail in hex_to_str

XRPLUtilsException::Utf8Error was a unit variant and its From impl
discarded the underlying core::str::Utf8Error, hiding the position and
valid-up-to information. Carry the Utf8Error so callers can diagnose
which byte was invalid.
---
 src/utils/exceptions.rs     | 10 ++--------
 src/utils/str_conversion.rs | 12 ++++++++++++
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/utils/exceptions.rs b/src/utils/exceptions.rs
index 7efc3031..9b19d4e6 100644
--- a/src/utils/exceptions.rs
+++ b/src/utils/exceptions.rs
@@ -39,8 +39,8 @@ pub enum XRPLUtilsException {
     FromHexError(#[from] hex::FromHexError),
     #[error("ParseInt error: {0}")]
     ParseIntError(#[from] core::num::ParseIntError),
-    #[error("Invalid UTF-8")]
-    Utf8Error,
+    #[error("Invalid UTF-8: {0}")]
+    Utf8Error(#[from] core::str::Utf8Error),
 }
 
 #[derive(Debug, Clone, PartialEq, Error)]
@@ -119,12 +119,6 @@ pub enum ISOCodeException {
     UnsupportedCurrencyRepresentation,
 }
 
-impl From<core::str::Utf8Error> for XRPLUtilsException {
-    fn from(_: core::str::Utf8Error) -> Self {
-        XRPLUtilsException::Utf8Error
-    }
-}
-
 impl From<serde_json::Error> for XRPLUtilsException {
     fn from(error: serde_json::Error) -> Self {
         XRPLUtilsException::SerdeJsonError(error.into())
diff --git a/src/utils/str_conversion.rs b/src/utils/str_conversion.rs
index 42dd6333..84acfabb 100644
--- a/src/utils/str_conversion.rs
+++ b/src/utils/str_conversion.rs
@@ -63,4 +63,16 @@ mod tests {
         let result = hex_to_str(Cow::Borrowed("ff"));
         assert!(result.is_err());
     }
+
+    #[test]
+    fn test_hex_to_str_invalid_utf8_preserves_detail() {
+        use crate::utils::exceptions::XRPLUtilsException;
+
+        // "41ff" decodes to [0x41, 0xff]: 'A' is valid, 0xff is not, so the
+        // Utf8Error should report `valid_up_to() == 1`.
+        match hex_to_str(Cow::Borrowed("41ff")).unwrap_err() {
+            XRPLUtilsException::Utf8Error(error) => assert_eq!(error.valid_up_to(), 1),
+            other => panic!("expected Utf8Error, got {other:?}"),
+        }
+    }
 }