feat(schedule): allow omission of schedule ID in ScheduleSignTransaction body

Signed-off-by: Ntege Daniel <danientege785@gmail.com>

Author: danielmarv

src/hiero_sdk_python/schedule/schedule_sign_transaction.py

@@ -61,17 +61,14 @@ def _build_proto_body(self):
         """
         Returns the protobuf body for the schedule sign transaction.
 
+        An unset schedule ID is omitted from the body rather than rejected locally, so the
+        network answers with INVALID_SCHEDULE_ID as it does for the other SDKs.
+
         Returns:
             ScheduleSignTransactionBody: The protobuf body for this transaction.
-
-        Raises:
-            ValueError: If schedule_id is not set.
         """
-        if self.schedule_id is None:
-            raise ValueError("Missing required ScheduleID")
-
         return ScheduleSignTransactionBody(
-            scheduleID=self.schedule_id._to_proto(),
+            scheduleID=self.schedule_id._to_proto() if self.schedule_id is not None else None,
         )
 
     def build_transaction_body(self):

tck/handlers/schedule.py

@@ -146,10 +146,8 @@ def _build_sign_schedule_transaction(params: SignScheduleParams) -> ScheduleSign
     """Build a ScheduleSignTransaction from TCK params."""
     transaction = ScheduleSignTransaction().set_grpc_deadline(DEFAULT_GRPC_TIMEOUT)
 
-    # The SDK requires an ID to serialize the transaction, while the TCK expects an
-    # omitted ID to reach the network and return INVALID_SCHEDULE_ID.
-    schedule_id = ScheduleId.from_string(params.scheduleId) if params.scheduleId is not None else ScheduleId()
-    transaction.set_schedule_id(schedule_id)
+    if params.scheduleId is not None:
+        transaction.set_schedule_id(ScheduleId.from_string(params.scheduleId))
 
     return transaction
 

tests/integration/schedule_sign_transaction_e2e_test.py

@@ -6,6 +6,7 @@
 
 import pytest
 
+from hiero_sdk_python.exceptions import PrecheckError
 from hiero_sdk_python.response_code import ResponseCode
 from hiero_sdk_python.schedule.schedule_id import ScheduleId
 from hiero_sdk_python.schedule.schedule_info_query import ScheduleInfoQuery
@@ -187,6 +188,17 @@ def test_integration_schedule_sign_transaction_fails_invalid_schedule_id(env):
     )
 
 
+@pytest.mark.integration
+def test_integration_schedule_sign_transaction_fails_without_schedule_id(env):
+    """Test that ScheduleSignTransaction fails precheck when no schedule ID is set.
+
+    The body omits scheduleID entirely, which the network rejects in pureChecks, so the
+    failure arrives as a precheck error rather than a receipt status.
+    """
+    with pytest.raises(PrecheckError, match="failed precheck with status: INVALID_SCHEDULE_ID"):
+        ScheduleSignTransaction().freeze_with(env.client).sign(env.operator_key).execute(env.client)
+
+
 def test_integration_schedule_sign_transaction_fails_with_already_executed(env):
     """Test that ScheduleSignTransaction fails when the schedule has already been executed."""
     account = env.create_account()

tests/unit/schedule_sign_transaction_test.py

@@ -76,12 +76,17 @@ def test_build_proto_body_with_schedule_id(schedule_id):
     assert proto_body.scheduleID == schedule_id._to_proto()
 
 
-def test_build_proto_body_without_schedule_id_raises_error():
-    """Test building protobuf body without a schedule ID."""
+def test_build_proto_body_without_schedule_id_omits_field():
+    """Test that building a protobuf body without a schedule ID leaves the field unset.
+
+    The network rejects a body with no scheduleID with INVALID_SCHEDULE_ID, so the
+    omission is left for it to answer instead of failing locally.
+    """
     schedule_sign_tx = ScheduleSignTransaction()
 
-    with pytest.raises(ValueError, match="Missing required ScheduleID"):
-        schedule_sign_tx._build_proto_body()
+    proto_body = schedule_sign_tx._build_proto_body()
+
+    assert not proto_body.HasField("scheduleID")
 
 
 def test_build_transaction_body_with_valid_schedule_id(mock_account_ids, schedule_id):