test: enhance NodeAddress tests with additional coverage

CHANGELOG.md

@@ -126,6 +126,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Renamed `pr-missing-linked-issue.yml` and `pr_missing_linked_issue.js` to `bot-pr-missing-linked-issue.yml` and `bot-pr-missing-linked-issue.js` respectively. Enhanced LinkBot PR comment with clickable hyperlinks to documentation for linking issues and creating issues. (#1264)
 - Enhance assignment bot to guard against users with spam PRs `.github/scripts/bot-assignment-check.sh`
 - Add CodeRabbit documentation review prompts for docs, sdk_users, and sdk_developers with priorities, philosophy, and edge case checks. ([#1236](https://github.com/hiero-ledger/hiero-sdk-python/issues/1236))
+- Enhance NodeAddress tests with additional coverage for proto conversion `tests/unit/node_address_test.py`
 
 ### Fixed
 - GFI workflow casing 

src/hiero_sdk_python/address_book/node_address.py

@@ -101,11 +101,8 @@ def _to_proto(self):
         if self._account_id:
             node_address_proto.nodeAccountId.CopyFrom(self._account_id._to_proto())
 
-        service_endpoints: List[Endpoint] = []
         for endpoint in self._addresses:
-            service_endpoints.append(endpoint._to_proto())
-
-        node_address_proto.serviceEndpoint = service_endpoints
+            node_address_proto.serviceEndpoint.append(endpoint._to_proto())
 
         return node_address_proto
 

tests/unit/node_address_test.py

@@ -1,8 +1,9 @@
+import binascii
 import pytest
 from hiero_sdk_python.account.account_id import AccountId
 from hiero_sdk_python.address_book.endpoint import Endpoint
 from hiero_sdk_python.address_book.node_address import NodeAddress
-
+from hiero_sdk_python.hapi.services.basic_types_pb2 import NodeAddress as NodeAddressProto
 pytestmark = pytest.mark.unit
 
 def test_init():
@@ -55,4 +56,188 @@ def test_string_representation():
     assert "NodeAccountId: 0.0.123" in result
     assert "CertHash: 73616d706c652d636572742d68617368" in result  # hex representation of sample-cert-hash
     assert "NodeId: 1234" in result
-    assert "PubKey: sample-public-key" in result
+    assert "PubKey: sample-public-key" in result
+
+
+def test_to_proto():
+    """Test conversion of NodeAddress to protobuf with endpoints."""
+    account_id = AccountId(0, 0, 123)
+    endpoints = [
+        Endpoint(address=bytes("192.168.1.1", "utf-8"), port=8080, domain_name="example1.com"),
+        Endpoint(address=bytes("192.168.1.2", "utf-8"), port=8081, domain_name="example2.com"),
+        Endpoint(address=bytes("192.168.1.3", "utf-8"), port=8082, domain_name="example3.com"),
+    ]
+    node_address = NodeAddress(
+        public_key="sample-public-key",
+        account_id=account_id,
+        node_id=1234,
+        cert_hash=b"sample-cert-hash",
+        addresses=endpoints,
+        description="Sample Node"
+    )
+
+    node_address_proto = node_address._to_proto()
+    # Protect against breaking changes - verify return type
+    assert isinstance(node_address_proto, NodeAddressProto)
+    # Scalars
+    assert node_address_proto.RSA_PubKey == "sample-public-key"
+    assert node_address_proto.nodeId == 1234
+    assert node_address_proto.nodeCertHash == b"sample-cert-hash"
+    assert node_address_proto.description == "Sample Node"
+
+    # AccountId
+    assert node_address_proto.nodeAccountId.shardNum == 0
+    assert node_address_proto.nodeAccountId.realmNum == 0
+    assert node_address_proto.nodeAccountId.accountNum == 123
+
+    # ServiceEndpoint
+    # Verify all endpoints are serialized
+    assert len(node_address_proto.serviceEndpoint) == 3
+    for i, ep_proto in enumerate(node_address_proto.serviceEndpoint):
+        assert ep_proto.ipAddressV4 == endpoints[i]._address
+        assert ep_proto.port == endpoints[i]._port
+        assert ep_proto.domain_name == endpoints[i]._domain_name
+
+
+def test_from_dict():
+    """Test creation of NodeAddress from a dictionary with hex cert hash."""
+    node_dict = {
+        "public_key": "sample-public-key",
+        "node_account_id": "0.0.123",
+        "node_id": 1234,
+        "node_cert_hash": binascii.hexlify(b"sample-cert-hash").decode("utf-8"),
+        "description": "Sample Node",
+        "service_endpoints": [
+            {"ip_address_v4": "192.168.1.1", "port": 8080, "domain_name": "example.com"}
+        ],
+    }
+
+    # Create NodeAddress from dict
+    node_address = NodeAddress._from_dict(node_dict)
+
+    # Protect against breaking changes - verify return type
+    assert isinstance(node_address, NodeAddress)
+
+    assert node_address._public_key == "sample-public-key"
+    assert node_address._account_id == AccountId.from_string("0.0.123")
+    assert node_address._node_id == 1234
+    assert node_address._cert_hash == b"sample-cert-hash"
+    assert node_address._description == "Sample Node"
+    assert len(node_address._addresses) == 1
+
+
+def test_from_dict_with_0x_prefix():
+    """Test _from_dict handles cert hash with 0x prefix."""
+    node_dict = {
+        "public_key": "sample-public-key",
+        "node_account_id": "0.0.123",
+        "node_id": 1234,
+        "node_cert_hash": "0x" + binascii.hexlify(b"sample-cert-hash").decode("utf-8"),
+        "description": "Sample Node",
+        "service_endpoints": [],
+    }
+
+    node_address = NodeAddress._from_dict(node_dict)
+
+    assert node_address._cert_hash == b"sample-cert-hash"
+
+
+def test_from_proto():
+    """Test creation of NodeAddress from protobuf with endpoint."""
+    account_id_proto = AccountId(0, 0, 123)._to_proto()
+    endpoint_proto = Endpoint(
+        address=bytes("192.168.1.1", "utf-8"),
+        port=8080,
+        domain_name="example.com"
+    )._to_proto()
+
+    # Create NodeAddressProto
+    node_address_proto = NodeAddressProto(
+        RSA_PubKey="sample-public-key",
+        nodeAccountId=account_id_proto,
+        nodeId=1234,
+        nodeCertHash=b"sample-cert-hash",
+        description="Sample Node",
+    )
+    node_address_proto.serviceEndpoint.append(endpoint_proto)
+
+    node_address = NodeAddress._from_proto(node_address_proto)
+
+    # Protect against breaking changes - verify return type
+    assert isinstance(node_address, NodeAddress)
+
+    assert node_address._public_key == "sample-public-key"
+    assert node_address._account_id == AccountId(0, 0, 123)
+    assert node_address._node_id == 1234
+    assert node_address._cert_hash == b"sample-cert-hash"
+    assert node_address._description == "Sample Node"
+    assert len(node_address._addresses) == 1
+
+
+def test_round_trip():
+    """Ensure NodeAddress → Proto → NodeAddress round trip works."""
+    account_id = AccountId(0, 0, 123)
+    endpoint = Endpoint(
+        address=bytes("192.168.1.1", "utf-8"),
+        port=8080,
+        domain_name="example.com"
+    )
+
+    # Create NodeAddress
+    node_address = NodeAddress(
+        public_key="sample-public-key",
+        account_id=account_id,
+        node_id=1234,
+        cert_hash=b"sample-cert-hash",
+        addresses=[endpoint],
+        description="Sample Node"
+    )
+
+    # Convert to proto
+    proto = node_address._to_proto()
+    # Convert back from proto
+    node_address2 = NodeAddress._from_proto(proto)
+
+    # Assert all fields are equal
+    assert node_address._public_key == node_address2._public_key
+    assert node_address._account_id == node_address2._account_id
+    assert node_address._node_id == node_address2._node_id
+    assert node_address._cert_hash == node_address2._cert_hash
+    assert node_address._description == node_address2._description
+    # Verify addresses match
+    assert len(node_address._addresses) == len(node_address2._addresses)
+    for i, endpoint in enumerate(node_address._addresses):
+        assert endpoint._address == node_address2._addresses[i]._address
+        assert endpoint._port == node_address2._addresses[i]._port
+        assert endpoint._domain_name == node_address2._addresses[i]._domain_name
+
+
+def test_empty_addresses():
+    """Test NodeAddress with no endpoints produces empty serviceEndpoint."""
+    node_address = NodeAddress(
+        public_key="sample-public-key",
+        account_id=AccountId(0, 0, 123),
+        node_id=1234,
+        cert_hash=b"sample-cert-hash",
+        addresses=[],
+        description="No endpoints"
+    )
+
+    proto = node_address._to_proto()
+    assert len(proto.serviceEndpoint) == 0
+
+def test_to_proto_none_account_id():
+    """Test _to_proto handles None account_id gracefully."""
+    node_address = NodeAddress(
+        public_key="sample-public-key",
+        account_id=None,
+        node_id=1234,
+        cert_hash=b"sample-cert-hash",
+        addresses=[],
+        description="No account"
+    )
+
+    proto = node_address._to_proto()
+
+    # Should not have nodeAccountId set
+    assert not proto.HasField('nodeAccountId')