Add hex codec traits for Transaction

diff --git a/api/primitives/all-features.txt b/api/primitives/all-features.txt
index bd392765..71be4b39 100644
--- a/api/primitives/all-features.txt
+++ b/api/primitives/all-features.txt
@@ -364,6 +364,7 @@ impl core::error::Error for bitcoin_primitives::script::ScriptBufDecoderError
 impl core::error::Error for bitcoin_primitives::script::WitnessScriptSizeError
 impl core::error::Error for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::error::Error for bitcoin_primitives::transaction::ParseOutPointError
+impl core::error::Error for bitcoin_primitives::transaction::ParseTransactionError
 impl core::error::Error for bitcoin_primitives::transaction::TransactionDecoderError
 impl core::error::Error for bitcoin_primitives::transaction::TxInDecoderError
 impl core::error::Error for bitcoin_primitives::transaction::TxMerkleNodeDecoderError
@@ -397,6 +398,7 @@ impl core::fmt::Debug for bitcoin_primitives::script::WitnessScriptSizeError
 impl core::fmt::Debug for bitcoin_primitives::transaction::OutPoint
 impl core::fmt::Debug for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::fmt::Debug for bitcoin_primitives::transaction::ParseOutPointError
+impl core::fmt::Debug for bitcoin_primitives::transaction::ParseTransactionError
 impl core::fmt::Debug for bitcoin_primitives::transaction::Transaction
 impl core::fmt::Debug for bitcoin_primitives::transaction::TransactionDecoderError
 impl core::fmt::Debug for bitcoin_primitives::transaction::TxIn
@@ -431,6 +433,8 @@ impl core::fmt::Display for bitcoin_primitives::script::WitnessScriptSizeError
 impl core::fmt::Display for bitcoin_primitives::transaction::OutPoint
 impl core::fmt::Display for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::fmt::Display for bitcoin_primitives::transaction::ParseOutPointError
+impl core::fmt::Display for bitcoin_primitives::transaction::ParseTransactionError
+impl core::fmt::Display for bitcoin_primitives::transaction::Transaction
 impl core::fmt::Display for bitcoin_primitives::transaction::TransactionDecoderError
 impl core::fmt::Display for bitcoin_primitives::transaction::TxInDecoderError
 impl core::fmt::Display for bitcoin_primitives::transaction::TxMerkleNodeDecoderError
@@ -449,6 +453,7 @@ impl core::fmt::LowerHex for bitcoin_primitives::Wtxid
 impl core::fmt::LowerHex for bitcoin_primitives::pow::CompactTarget
 impl core::fmt::LowerHex for bitcoin_primitives::script::ScriptHash
 impl core::fmt::LowerHex for bitcoin_primitives::script::WScriptHash
+impl core::fmt::LowerHex for bitcoin_primitives::transaction::Transaction
 impl core::fmt::UpperHex for bitcoin_primitives::BlockHash
 impl core::fmt::UpperHex for bitcoin_primitives::Ntxid
 impl core::fmt::UpperHex for bitcoin_primitives::TxMerkleNode
@@ -459,6 +464,7 @@ impl core::fmt::UpperHex for bitcoin_primitives::Wtxid
 impl core::fmt::UpperHex for bitcoin_primitives::pow::CompactTarget
 impl core::fmt::UpperHex for bitcoin_primitives::script::ScriptHash
 impl core::fmt::UpperHex for bitcoin_primitives::script::WScriptHash
+impl core::fmt::UpperHex for bitcoin_primitives::transaction::Transaction
 impl core::hash::Hash for bitcoin_primitives::BlockHash
 impl core::hash::Hash for bitcoin_primitives::Ntxid
 impl core::hash::Hash for bitcoin_primitives::TxMerkleNode
@@ -541,6 +547,7 @@ impl core::marker::Freeze for bitcoin_primitives::transaction::OutPoint
 impl core::marker::Freeze for bitcoin_primitives::transaction::OutPointDecoder
 impl core::marker::Freeze for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::marker::Freeze for bitcoin_primitives::transaction::ParseOutPointError
+impl core::marker::Freeze for bitcoin_primitives::transaction::ParseTransactionError
 impl core::marker::Freeze for bitcoin_primitives::transaction::Transaction
 impl core::marker::Freeze for bitcoin_primitives::transaction::TransactionDecoder
 impl core::marker::Freeze for bitcoin_primitives::transaction::TransactionDecoderError
@@ -602,6 +609,7 @@ impl core::marker::Send for bitcoin_primitives::transaction::OutPoint
 impl core::marker::Send for bitcoin_primitives::transaction::OutPointDecoder
 impl core::marker::Send for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::marker::Send for bitcoin_primitives::transaction::ParseOutPointError
+impl core::marker::Send for bitcoin_primitives::transaction::ParseTransactionError
 impl core::marker::Send for bitcoin_primitives::transaction::Transaction
 impl core::marker::Send for bitcoin_primitives::transaction::TransactionDecoder
 impl core::marker::Send for bitcoin_primitives::transaction::TransactionDecoderError
@@ -706,6 +714,7 @@ impl core::marker::Sync for bitcoin_primitives::transaction::OutPoint
 impl core::marker::Sync for bitcoin_primitives::transaction::OutPointDecoder
 impl core::marker::Sync for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::marker::Sync for bitcoin_primitives::transaction::ParseOutPointError
+impl core::marker::Sync for bitcoin_primitives::transaction::ParseTransactionError
 impl core::marker::Sync for bitcoin_primitives::transaction::Transaction
 impl core::marker::Sync for bitcoin_primitives::transaction::TransactionDecoder
 impl core::marker::Sync for bitcoin_primitives::transaction::TransactionDecoderError
@@ -767,6 +776,7 @@ impl core::marker::Unpin for bitcoin_primitives::transaction::OutPoint
 impl core::marker::Unpin for bitcoin_primitives::transaction::OutPointDecoder
 impl core::marker::Unpin for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::marker::Unpin for bitcoin_primitives::transaction::ParseOutPointError
+impl core::marker::Unpin for bitcoin_primitives::transaction::ParseTransactionError
 impl core::marker::Unpin for bitcoin_primitives::transaction::Transaction
 impl core::marker::Unpin for bitcoin_primitives::transaction::TransactionDecoder
 impl core::marker::Unpin for bitcoin_primitives::transaction::TransactionDecoderError
@@ -829,6 +839,7 @@ impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::OutPointDecoder
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::ParseOutPointError
+impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::ParseTransactionError
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::Transaction
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::TransactionDecoder
 impl core::panic::unwind_safe::RefUnwindSafe for bitcoin_primitives::transaction::TransactionDecoderError
@@ -890,6 +901,7 @@ impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::O
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::OutPointDecoder
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::OutPointDecoderError
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::ParseOutPointError
+impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::ParseTransactionError
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::Transaction
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::TransactionDecoder
 impl core::panic::unwind_safe::UnwindSafe for bitcoin_primitives::transaction::TransactionDecoderError
@@ -919,6 +931,7 @@ impl core::str::traits::FromStr for bitcoin_primitives::Wtxid
 impl core::str::traits::FromStr for bitcoin_primitives::script::ScriptHash
 impl core::str::traits::FromStr for bitcoin_primitives::script::WScriptHash
 impl core::str::traits::FromStr for bitcoin_primitives::transaction::OutPoint
+impl core::str::traits::FromStr for bitcoin_primitives::transaction::Transaction
 impl serde::ser::Serialize for bitcoin_primitives::BlockHash
 impl serde::ser::Serialize for bitcoin_primitives::Ntxid
 impl serde::ser::Serialize for bitcoin_primitives::TxMerkleNode
@@ -1730,6 +1743,8 @@ pub fn bitcoin_primitives::transaction::ParseOutPointError::eq(&self, other: &bi
 pub fn bitcoin_primitives::transaction::ParseOutPointError::fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
 pub fn bitcoin_primitives::transaction::ParseOutPointError::from(never: core::convert::Infallible) -> Self
 pub fn bitcoin_primitives::transaction::ParseOutPointError::source(&self) -> core::option::Option<&(dyn core::error::Error + 'static)>
+pub fn bitcoin_primitives::transaction::ParseTransactionError::fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
+pub fn bitcoin_primitives::transaction::ParseTransactionError::source(&self) -> core::option::Option<&(dyn core::error::Error + 'static)>
 pub fn bitcoin_primitives::transaction::Transaction::arbitrary(u: &mut arbitrary::unstructured::Unstructured<'a>) -> arbitrary::error::Result<Self>
 pub fn bitcoin_primitives::transaction::Transaction::clone(&self) -> bitcoin_primitives::transaction::Transaction
 pub fn bitcoin_primitives::transaction::Transaction::cmp(&self, other: &Self) -> core::cmp::Ordering
@@ -1740,6 +1755,7 @@ pub fn bitcoin_primitives::transaction::Transaction::decoder() -> Self::Decoder
 pub fn bitcoin_primitives::transaction::Transaction::encoder(&self) -> Self::Encoder
 pub fn bitcoin_primitives::transaction::Transaction::eq(&self, other: &bitcoin_primitives::transaction::Transaction) -> bool
 pub fn bitcoin_primitives::transaction::Transaction::fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result
+pub fn bitcoin_primitives::transaction::Transaction::from_str(s: &str) -> core::result::Result<Self, Self::Err>
 pub fn bitcoin_primitives::transaction::Transaction::hash<__H: core::hash::Hasher>(&self, state: &mut __H)
 pub fn bitcoin_primitives::transaction::Transaction::is_coinbase(&self) -> bool
 pub fn bitcoin_primitives::transaction::Transaction::partial_cmp(&self, other: &Self) -> core::option::Option<core::cmp::Ordering>
@@ -1957,6 +1973,7 @@ pub struct bitcoin_primitives::transaction::OutPoint
 pub struct bitcoin_primitives::transaction::OutPointDecoder(_)
 pub struct bitcoin_primitives::transaction::OutPointDecoderError(_)
 pub struct bitcoin_primitives::transaction::OutPointEncoder<'e>(_)
+pub struct bitcoin_primitives::transaction::ParseTransactionError(_)
 pub struct bitcoin_primitives::transaction::Transaction
 pub struct bitcoin_primitives::transaction::TransactionDecoder
 pub struct bitcoin_primitives::transaction::TransactionDecoderError(_)
@@ -2061,6 +2078,7 @@ pub type bitcoin_primitives::transaction::OutPointDecoder::Error = bitcoin_primi
 pub type bitcoin_primitives::transaction::OutPointDecoder::Output = bitcoin_primitives::transaction::OutPoint
 pub type bitcoin_primitives::transaction::Transaction::Decoder = bitcoin_primitives::transaction::TransactionDecoder
 pub type bitcoin_primitives::transaction::Transaction::Encoder<'e> where Self: 'e = bitcoin_primitives::transaction::TransactionEncoder<'e>
+pub type bitcoin_primitives::transaction::Transaction::Err = bitcoin_primitives::transaction::ParseTransactionError
 pub type bitcoin_primitives::transaction::TransactionDecoder::Error = bitcoin_primitives::transaction::TransactionDecoderError
 pub type bitcoin_primitives::transaction::TransactionDecoder::Output = bitcoin_primitives::transaction::Transaction
 pub type bitcoin_primitives::transaction::TxIn::Decoder = bitcoin_primitives::transaction::TxInDecoder
diff --git a/bitcoin/src/blockdata/transaction.rs b/bitcoin/src/blockdata/transaction.rs
index 5336a9c0..5bba509d 100644
--- a/bitcoin/src/blockdata/transaction.rs
+++ b/bitcoin/src/blockdata/transaction.rs
@@ -33,7 +33,7 @@ use crate::{internal_macros, Amount, FeeRate, Sequence, SignedAmount};
 
 #[rustfmt::skip]            // Keep public re-exports separate.
 #[doc(inline)]
-pub use primitives::transaction::{OutPoint, ParseOutPointError, Transaction, Ntxid, Txid, Wtxid, Version, TxIn, TxOut};
+pub use primitives::transaction::{OutPoint, ParseTransactionError, ParseOutPointError, Transaction, Ntxid, Txid, Wtxid, Version, TxIn, TxOut};
 
 impl Encodable for Txid {
     fn consensus_encode<W: Write + ?Sized>(&self, w: &mut W) -> Result<usize, io::Error> {
diff --git a/primitives/src/lib.rs b/primitives/src/lib.rs
index 75f8b7f3..af450889 100644
--- a/primitives/src/lib.rs
+++ b/primitives/src/lib.rs
@@ -115,3 +115,141 @@ pub(crate) fn compact_size_encode(value: usize) -> ArrayVec<u8, 9> {
     let encoder = encoding::CompactSizeEncoder::new(value);
     ArrayVec::from_slice(encoder.current_chunk())
 }
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+use core::{fmt, convert};
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+use encoding::{Decodable, Decoder};
+#[cfg(all(feature = "hex", feature = "alloc"))]
+use internals::write_err;
+
+/// An error type for errors that can occur during parsing of a `Decodable` type from hex.
+#[cfg(all(feature = "hex", feature = "alloc"))]
+enum ParsePrimitiveError<T: Decodable> {
+    /// Tried to decode an odd length string
+    OddLengthString(hex::error::OddLengthStringError),
+    /// Encountered an invalid hex character
+    InvalidChar(hex::error::InvalidCharError),
+    /// A decode error from `consensus_encoding`
+    Decode(<T::Decoder as Decoder>::Error),
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl<T: Decodable> fmt::Debug for ParsePrimitiveError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::OddLengthString(ref e) => write_err!(f, "odd length string"; e),
+            Self::InvalidChar(ref e) => write_err!(f, "invalid character"; e),
+            // Decoder error types don't have Debug, so we only provide this generic error
+            Self::Decode(_) => write!(f, "failure decoding hex string into {}", core::any::type_name::<T>()),
+        }
+    }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl<T: Decodable> fmt::Display for ParsePrimitiveError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&self, f) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl<T: Decodable> From<hex::DecodeVariableLengthBytesError> for ParsePrimitiveError<T> {
+    fn from(dec_err: hex::DecodeVariableLengthBytesError) -> Self {
+        use hex::DecodeVariableLengthBytesError as D;
+
+        match dec_err {
+            D::InvalidChar(err) => Self::InvalidChar(err),
+            D::OddLengthString(err) => Self::OddLengthString(err),
+        }
+    }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl<T: Decodable> From<convert::Infallible> for ParsePrimitiveError<T> {
+    fn from(never: convert::Infallible) -> Self { match never {} }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc", feature = "std"))]
+impl<T: Decodable> std::error::Error for ParsePrimitiveError<T> {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::OddLengthString(ref e) => Some(e),
+            Self::InvalidChar(ref e) => Some(e),
+            Self::Decode(_) => None,
+        }
+    }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+pub(crate) mod hex_codec {
+    use super::{fmt, Decodable, ParsePrimitiveError};
+
+    use encoding::{Encodable, EncodableByteIter};
+    use hex_unstable::{BytesToHexIter, Case};
+
+    /// Writes an Encodable object to the given formatter in the requested case.
+    #[inline]
+    fn hex_write_with_case<T: Encodable + Decodable>(obj: &HexPrimitive<T>, f: &mut fmt::Formatter, case: Case) -> fmt::Result {
+        let iter = BytesToHexIter::new(
+            encoding::EncodableByteIter::new(obj.0),
+            case
+        );
+        let collection = iter.collect::<alloc::string::String>();
+        f.pad(&collection)
+    }
+
+    /// Hex encoding wrapper type for Encodable + Decodable types.
+    ///
+    /// Provides default implementations for `Display`, `Debug`, `LowerHex`, and `UpperHex`.
+    /// Also provides [`Self::from_str`] for parsing a string to a `T`.
+    /// This can be used to implement hex display traits for any encodable types.
+    pub(crate) struct HexPrimitive<'a, T: Encodable + Decodable>(pub &'a T);
+
+    impl<'a, T: Encodable + Decodable> IntoIterator for &HexPrimitive<'a, T> {
+        type Item = u8;
+        type IntoIter = EncodableByteIter<'a, T>;
+
+        fn into_iter(self) -> Self::IntoIter {
+            EncodableByteIter::new(self.0)
+        }
+    }
+
+    impl<T: Encodable + Decodable> HexPrimitive<'_, T> {
+        /// Parses a given string into an instance of the type `T`.
+        ///
+        /// Since `FromStr` would return an instance of Self and thus a &T, this function
+        /// is implemented directly on the struct to return the owned instance of T.
+        /// Other `FromStr` implementations can directly return the result of
+        /// [`HexPrimitive::from_str`].
+        ///
+        /// # Errors
+        ///
+        /// [`ParsePrimitiveError::OddLengthString`] if the input string is an odd length.
+        /// [`ParsePrimitiveError::Decode`] if an error occurs during decoding of the object.
+        pub(crate) fn from_str(s: &str) -> Result<T, ParsePrimitiveError<T>> {
+            let bytes = hex::decode_to_vec(s).map_err(ParsePrimitiveError::from)?;
+
+            encoding::decode_from_slice(&bytes).map_err(ParsePrimitiveError::Decode)
+        }
+    }
+
+    impl<T: Encodable + Decodable> fmt::Display for HexPrimitive<'_, T> {
+        #[inline]
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(self, f) }
+    }
+
+    impl<T: Encodable + Decodable> fmt::Debug for HexPrimitive<'_, T> {
+        #[inline]
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(self, f) }
+    }
+
+    impl<T: Encodable + Decodable> fmt::LowerHex for HexPrimitive<'_, T> {
+        #[inline]
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { hex_write_with_case(self, f, Case::Lower) }
+    }
+
+    impl<T: Encodable + Decodable> fmt::UpperHex for HexPrimitive<'_, T> {
+        #[inline]
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { hex_write_with_case(self, f, Case::Upper) }
+    }
+}
diff --git a/primitives/src/transaction.rs b/primitives/src/transaction.rs
index 335daf94..4084c92f 100644
--- a/primitives/src/transaction.rs
+++ b/primitives/src/transaction.rs
@@ -29,7 +29,7 @@ use internals::array::ArrayExt as _;
 use internals::write_err;
 #[cfg(feature = "serde")]
 use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
-#[cfg(feature = "hex")]
+#[cfg(all(feature = "hex", feature = "alloc"))]
 use units::parse_int;
 
 #[cfg(feature = "alloc")]
@@ -371,6 +371,47 @@ impl Encodable for Transaction {
     }
 }
 
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl core::str::FromStr for Transaction {
+    type Err = ParseTransactionError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> { crate::hex_codec::HexPrimitive::from_str(s).map_err(ParseTransactionError) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl fmt::Display for Transaction {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&crate::hex_codec::HexPrimitive(self), f) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl fmt::LowerHex for Transaction {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&crate::hex_codec::HexPrimitive(self), f) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl fmt::UpperHex for Transaction {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::UpperHex::fmt(&crate::hex_codec::HexPrimitive(self), f) }
+}
+
+/// An error that occurs during parsing of a [`Transaction`] from a hex string.
+#[cfg(all(feature = "hex", feature = "alloc"))]
+pub struct ParseTransactionError(crate::ParsePrimitiveError<Transaction>);
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl fmt::Debug for ParseTransactionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&self.0, f) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc"))]
+impl fmt::Display for ParseTransactionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&self, f) }
+}
+
+#[cfg(all(feature = "hex", feature = "alloc", feature = "std"))]
+impl std::error::Error for ParseTransactionError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { std::error::Error::source(&self.0) }
+}
+
 /// The decoder for the [`Transaction`] type.
 #[cfg(feature = "alloc")]
 pub struct TransactionDecoder {
@@ -1517,6 +1558,8 @@ mod tests {
     #[cfg(feature = "hex")]
     use alloc::string::ToString;
     use alloc::{format, vec};
+    #[cfg(feature = "hex")]
+    use core::str::FromStr as _;
 
     use encoding::Encoder as _;
     #[cfg(feature = "hex")]
@@ -1599,6 +1642,91 @@ mod tests {
         assert!(tx > tx_orig);
     }
 
+    #[test]
+    #[cfg(feature = "hex")]
+    fn transaction_hex_display() {
+        let txin = TxIn {
+            previous_output: OutPoint {
+                txid: Txid::from_byte_array([0xAA; 32]), // Arbitrary invalid dummy value.
+                vout: 0,
+            },
+            script_sig: ScriptSigBuf::new(),
+            sequence: Sequence::MAX,
+            witness: Witness::new(),
+        };
+
+        let txout = TxOut {
+            amount: Amount::from_sat(123_456_789).unwrap(),
+            script_pubkey: ScriptPubKeyBuf::new(),
+        };
+
+        let tx_orig = Transaction {
+            version: Version::ONE,
+            lock_time: absolute::LockTime::from_consensus(1_765_112_030), // The time this was written
+            inputs: vec![txin],
+            outputs: vec![txout],
+        };
+
+        let encoded_tx = "0100000001aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa0000000000ffffffff0115cd5b070000000000de783569";
+        let lower_hex_tx = format!("{:x}", tx_orig);
+        let upper_hex_tx = format!("{:X}", tx_orig);
+
+        // All of these should yield a lowercase hex
+        assert_eq!(encoded_tx, lower_hex_tx);
+        assert_eq!(encoded_tx, format!("{}", tx_orig));
+
+        // And this should yield uppercase hex
+        let upper_encoded = encoded_tx
+            .chars()
+            .map(|chr| chr.to_ascii_uppercase())
+            .collect::<alloc::string::String>();
+        assert_eq!(upper_encoded, upper_hex_tx);
+    }
+
+    #[test]
+    #[cfg(feature = "hex")]
+    fn transaction_from_hex_str_round_trip() {
+        // Create a transaction and convert it to a hex string
+        let tx = Transaction {
+            version: Version::TWO,
+            lock_time: absolute::LockTime::ZERO,
+            inputs: vec![segwit_tx_in(), segwit_tx_in()],
+            outputs: vec![tx_out(), tx_out()],
+        };
+
+        let lower_hex_tx = format!("{:x}", tx);
+        let upper_hex_tx = format!("{:X}", tx);
+
+        // Parse the hex strings back into transactions
+        let parsed_lower = Transaction::from_str(&lower_hex_tx).unwrap();
+        let parsed_upper = Transaction::from_str(&upper_hex_tx).unwrap();
+
+        // The parsed transaction should match the originals
+        assert_eq!(tx, parsed_lower);
+        assert_eq!(tx, parsed_upper);
+    }
+
+    #[test]
+    #[cfg(feature = "hex")]
+    fn transaction_from_hex_str_error() {
+        use crate::ParsePrimitiveError;
+
+        // OddLengthString error
+        let odd = "abc"; // 3 chars, odd length
+        let err = Transaction::from_str(odd).unwrap_err();
+        assert!(matches!(err, ParseTransactionError(ParsePrimitiveError::OddLengthString(..))));
+
+        // InvalidChar error
+        let invalid = "zz";
+        let err = Transaction::from_str(invalid).unwrap_err();
+        assert!(matches!(err, ParseTransactionError(ParsePrimitiveError::InvalidChar(..))));
+
+        // Decode error
+        let bad = "deadbeef00"; // arbitrary even-length hex that will fail decoding
+        let err = Transaction::from_str(bad).unwrap_err();
+        assert!(matches!(err, ParseTransactionError(ParsePrimitiveError::Decode(..))));
+    }
+
     #[test]
     #[cfg(feature = "hex")]
     fn outpoint_from_str() {