feat: added ticket_sequence to Transaction class common fields (#428)

* added ticket_sequence to Transaction class common

* added simple ticket_sequence added test

* unit tested and threw errors on ticket seq

* fixed up name of tests

* made ticket sequence test more readable

* changed to long string

* whitespace

* Updated CHANGELOG.md with ticket_sequence

* Remove empty lines from CHANGELOG

* Removed empty lines from CHANGELOG v2

* Update CHANGELOG.md for clearer common field naming

Co-authored-by: Elliot Lee <github.public@intelliot.com>

* Update Sequence to sequence for readability

Co-authored-by: Elliot Lee <github.public@intelliot.com>

Co-authored-by: Elliot Lee <github.public@intelliot.com>

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Function to parse the final account balances from a transaction's metadata
 - Function to parse order book changes from a transaction's metadata
 - Support for Ed25519 seeds that don't use the `sEd` prefix
+- Common field `ticket_sequence` to Transaction class
 
 ### Fixed:
 - Typing for factory classmethods on models

tests/unit/models/transactions/test_transaction.py

@@ -8,6 +8,8 @@
 _ACCOUNT = "r9LqNeG6qHxjeUocjvVki2XR35weJ9mZgQ"
 _FEE = "0.00001"
 _SEQUENCE = 19048
+_TICKET_SEQUENCE = 20510
+_ACCOUNT_TXN_ID = "66F3D6158CAB6E53405F8C264DB39F07D8D0454433A63DDFB98218ED1BC99B60"
 
 
 class TestTransaction(TestCase):
@@ -79,3 +81,44 @@ def test_to_dict_flag_list(self):
         expected_flags = 0b111
         value = tx.to_dict()["flags"]
         self.assertEqual(value, expected_flags)
+
+    def test_to_dict_ticket_sequence(self):
+        tx = Transaction(
+            account=_ACCOUNT,
+            fee=_FEE,
+            ticket_sequence=_TICKET_SEQUENCE,
+            transaction_type=TransactionType.ACCOUNT_DELETE,
+        )
+        value = tx.to_dict()["ticket_sequence"]
+        self.assertEqual(value, _TICKET_SEQUENCE)
+
+    def test_to_dict_ticket_sequence_with_sequence_zero(self):
+        tx = Transaction(
+            account=_ACCOUNT,
+            fee=_FEE,
+            sequence=0,
+            ticket_sequence=_TICKET_SEQUENCE,
+            transaction_type=TransactionType.ACCOUNT_DELETE,
+        )
+        value = tx.to_dict()["ticket_sequence"]
+        self.assertEqual(value, _TICKET_SEQUENCE)
+
+    def test_throws_when_ticket_sequence_and_sequence_both_nonzero(self):
+        with self.assertRaises(XRPLModelException):
+            Transaction(
+                account=_ACCOUNT,
+                fee=_FEE,
+                sequence=_SEQUENCE,
+                ticket_sequence=_TICKET_SEQUENCE,
+                transaction_type=TransactionType.ACCOUNT_DELETE,
+            )
+
+    def test_throws_when_ticket_sequence_and_account_tx_in_both_included(self):
+        with self.assertRaises(XRPLModelException):
+            Transaction(
+                account=_ACCOUNT,
+                fee=_FEE,
+                account_txn_id=_ACCOUNT_TXN_ID,
+                ticket_sequence=_TICKET_SEQUENCE,
+                transaction_type=TransactionType.ACCOUNT_DELETE,
+            )

xrpl/models/transactions/transaction.py

@@ -243,12 +243,30 @@ class Transaction(BaseModel):
     added during signing.
     """
 
+    ticket_sequence: Optional[int] = None
+    """
+    The sequence number of the ticket to use in place of a Sequence number. If
+    this is provided, sequence must be 0. Cannot be used with account_txn_id.
+    """
+
     txn_signature: Optional[str] = None
     """
     The cryptographic signature from the sender that authorizes this
     transaction. Automatically added during signing.
     """
 
+    def _get_errors(self: Transaction) -> Dict[str, str]:
+        errors = super()._get_errors()
+        if self.ticket_sequence is not None and (
+            (self.sequence is not None and self.sequence != 0)
+            or self.account_txn_id is not None
+        ):
+            errors[
+                "Transaction"
+            ] = """If ticket_sequence is provided,
+            account_txn_id must be None and sequence must be None or 0"""
+        return errors
+
     def to_dict(self: Transaction) -> Dict[str, Any]:
         """
         Returns the dictionary representation of a Transaction.