fix: serialize index as hex string (#1687)

crates/rpc/rpc-types/Cargo.toml

@@ -27,4 +27,5 @@ jsonrpsee-types = { version = "0.16" }
 lru = "0.9"
 
 [dev-dependencies]
+rand = "0.8"
 reth-interfaces = { path = "../../interfaces", features = ["test-utils"] }

crates/rpc/rpc-types/src/eth/index.rs

@@ -19,7 +19,7 @@ impl Serialize for Index {
     where
         S: Serializer,
     {
-        serializer.serialize_str(&format!("{:x}", self.0))
+        serializer.serialize_str(&format!("0x{:x}", self.0))
     }
 }
 
@@ -71,3 +71,20 @@ impl<'a> Deserialize<'a> for Index {
         deserializer.deserialize_any(IndexVisitor)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rand::{thread_rng, Rng};
+
+    #[test]
+    fn test_serde_index_rand() {
+        let mut rng = thread_rng();
+        for _ in 0..100 {
+            let index = Index(rng.gen());
+            let val = serde_json::to_string(&index).unwrap();
+            let de: Index = serde_json::from_str(&val).unwrap();
+            assert_eq!(index, de);
+        }
+    }
+}