feat(core): add Debug and Display implementations for Txid types

Implements Display for Txid and TxidRef to show ids as hex
strings in Bitcoin's standard format (reverse byte order).

Implements Debug for Txid and TxidRef in internal order.

Author: alexanderwiederin

src/core/transaction.rs

@@ -1,4 +1,8 @@
-use std::{ffi::c_void, marker::PhantomData};
+use std::{
+    ffi::c_void,
+    fmt::{self, Debug, Display, Formatter},
+    marker::PhantomData,
+};
 
 use libbitcoinkernel_sys::{
     btck_Transaction, btck_TransactionInput, btck_TransactionOutPoint, btck_TransactionOutput,
@@ -653,7 +657,6 @@ pub trait TxidExt: AsPtr<btck_Txid> {
     }
 }
 
-#[derive(Debug)]
 pub struct Txid {
     inner: *mut btck_Txid,
 }
@@ -709,7 +712,22 @@ impl PartialEq<TxidRef<'_>> for Txid {
 
 impl Eq for Txid {}
 
-#[derive(Debug)]
+impl Debug for Txid {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "Txid({:?})", self.to_bytes())
+    }
+}
+
+impl Display for Txid {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        let bytes = self.to_bytes();
+        for byte in bytes.iter().rev() {
+            write!(f, "{:02x}", byte)?;
+        }
+        Ok(())
+    }
+}
+
 pub struct TxidRef<'a> {
     inner: *const btck_Txid,
     marker: PhantomData<&'a ()>,
@@ -765,6 +783,22 @@ impl PartialEq<Txid> for TxidRef<'_> {
     }
 }
 
+impl<'a> Debug for TxidRef<'a> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "Txid({:?})", self.to_bytes())
+    }
+}
+
+impl<'a> Display for TxidRef<'a> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        let bytes = self.to_bytes();
+        for byte in bytes.iter().rev() {
+            write!(f, "{:02x}", byte)?;
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1322,4 +1356,30 @@ mod tests {
 
         assert_eq!(iter_count, count);
     }
+
+    #[test]
+    fn test_txid_display() {
+        let (tx, _) = get_test_transactions();
+        let txid = tx.txid().to_owned();
+
+        let display = format!("{}", txid);
+
+        assert_eq!(
+            display,
+            "f3ac0618ad042336fbec1f88a4e965481b46cd3381a807591c78c75fdbae7d67"
+        );
+    }
+
+    #[test]
+    fn test_txid_ref_display() {
+        let (tx, _) = get_test_transactions();
+        let txid = tx.txid();
+
+        let display = format!("{}", txid);
+
+        assert_eq!(
+            display,
+            "f3ac0618ad042336fbec1f88a4e965481b46cd3381a807591c78c75fdbae7d67"
+        );
+    }
 }