fix(chain): Use network kind of TestnetKind in transparent addresses on Regtest (#9175)

* Use `TestnetKind` as transparent addr network kinds on Regtest

* Updates outdated error message

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: arya2

zebra-chain/src/parameters/network.rs

@@ -29,8 +29,7 @@ pub enum NetworkKind {
     /// A test network.
     Testnet,
 
-    /// Regtest mode, not yet implemented
-    // TODO: Add `new_regtest()` and `is_regtest` methods on `Network`.
+    /// Regtest mode
     Regtest,
 }
 
@@ -186,6 +185,16 @@ impl Network {
         }
     }
 
+    /// Returns [`NetworkKind::Testnet`] on Testnet and Regtest, or [`NetworkKind::Mainnet`] on Mainnet.
+    ///
+    /// This is used for transparent addresses, as the address prefix is the same on Regtest as it is on Testnet.
+    pub fn t_addr_kind(&self) -> NetworkKind {
+        match self {
+            Network::Mainnet => NetworkKind::Mainnet,
+            Network::Testnet(_) => NetworkKind::Testnet,
+        }
+    }
+
     /// Returns an iterator over [`Network`] variants.
     pub fn iter() -> impl Iterator<Item = Self> {
         [Self::Mainnet, Self::new_default_testnet()].into_iter()

zebra-chain/src/primitives/zcash_primitives.rs

@@ -351,10 +351,10 @@ pub(crate) fn transparent_output_address(
 
     match alt_addr {
         Some(zcash_primitives::legacy::TransparentAddress::PublicKeyHash(pub_key_hash)) => Some(
-            transparent::Address::from_pub_key_hash(network.kind(), pub_key_hash),
+            transparent::Address::from_pub_key_hash(network.t_addr_kind(), pub_key_hash),
         ),
         Some(zcash_primitives::legacy::TransparentAddress::ScriptHash(script_hash)) => Some(
-            transparent::Address::from_script_hash(network.kind(), script_hash),
+            transparent::Address::from_script_hash(network.t_addr_kind(), script_hash),
         ),
         None => None,
     }

zebra-consensus/src/error.rs

@@ -204,7 +204,7 @@ pub enum TransactionError {
     #[error("could not find a mempool transaction input UTXO in the best chain")]
     TransparentInputNotFound,
 
-    #[error("could not validate nullifiers and anchors on best chain: {0}")]
+    #[error("could not contextually validate transaction on best chain: {0}")]
     #[cfg_attr(any(test, feature = "proptest-impl"), proptest(skip))]
     // This error variant is at least 128 bytes
     ValidateContextError(Box<ValidateContextError>),