fix(chain): make FromHex consistent with ToHex for tx/block hashes (#3893)

zebra-chain/src/block/hash.rs

@@ -74,7 +74,8 @@ impl FromHex for Hash {
     type Error = <[u8; 32] as FromHex>::Error;
 
     fn from_hex<T: AsRef<[u8]>>(hex: T) -> Result<Self, Self::Error> {
-        let hash = <[u8; 32]>::from_hex(hex)?;
+        let mut hash = <[u8; 32]>::from_hex(hex)?;
+        hash.reverse();
 
         Ok(hash.into())
     }

zebra-chain/src/block/tests/prop.rs

@@ -2,6 +2,8 @@ use std::{env, io::ErrorKind};
 
 use proptest::{arbitrary::any, prelude::*, test_runner::Config};
 
+use hex::{FromHex, ToHex};
+
 use zebra_test::prelude::*;
 
 use crate::{
@@ -43,6 +45,15 @@ proptest! {
         prop_assert_eq!(hash, parsed);
     }
 
+    #[test]
+    fn block_hash_hex_roundtrip(hash in any::<Hash>()) {
+        zebra_test::init();
+
+        let hex_hash: String = hash.encode_hex();
+        let new_hash = Hash::from_hex(hex_hash).expect("hex hash should parse");
+        prop_assert_eq!(hash, new_hash);
+    }
+
     #[test]
     fn blockheader_roundtrip(header in any::<Header>()) {
         zebra_test::init();

zebra-chain/src/transaction/hash.rs

@@ -137,7 +137,8 @@ impl FromHex for Hash {
     type Error = <[u8; 32] as FromHex>::Error;
 
     fn from_hex<T: AsRef<[u8]>>(hex: T) -> Result<Self, Self::Error> {
-        let hash = <[u8; 32]>::from_hex(hex)?;
+        let mut hash = <[u8; 32]>::from_hex(hex)?;
+        hash.reverse();
 
         Ok(hash.into())
     }

zebra-chain/src/transaction/tests/prop.rs

@@ -6,6 +6,8 @@ use std::io::Cursor;
 
 use zebra_test::prelude::*;
 
+use hex::{FromHex, ToHex};
+
 use super::super::*;
 
 use crate::{
@@ -51,6 +53,15 @@ proptest! {
         }
     }
 
+    #[test]
+    fn transaction_hash_hex_roundtrip(hash in any::<Hash>()) {
+        zebra_test::init();
+
+        let hex_hash: String = hash.encode_hex();
+        let new_hash = Hash::from_hex(hex_hash).expect("hex hash should parse");
+        prop_assert_eq!(hash, new_hash);
+    }
+
     #[test]
     fn transaction_auth_digest_struct_display_roundtrip(auth_digest in any::<AuthDigest>()) {
         zebra_test::init();