CSHARP-4808: "Updating stale electionId and setVersion" even when electionId/setVersion match (#1201)

Author: BorisDog

src/MongoDB.Driver.Core/Core/Clusters/MultiServerCluster.cs

@@ -658,12 +658,12 @@ public ElectionInfo(int? setVersion, ElectionId electionId)
             public int? SetVersion => _setVersion;
             public ElectionId ElectionId => _electionId;
 
-            public ElectionInfo Compare(int? setVersion, ElectionId electionId, int maxWireVerion)
+            public ElectionInfo Compare(int? setVersion, ElectionId electionId, int maxWireVersion)
             {
                 var newElectionId = _electionId;
                 var newSetVersion = _setVersion;
 
-                if (Feature.ElectionIdPriorityInSDAM.IsSupported(maxWireVerion))
+                if (Feature.ElectionIdPriorityInSDAM.IsSupported(maxWireVersion))
                 {
                     var electionIdOrder = Compare(electionId);
                     var isGreaterOrEqual = electionIdOrder < 0 || electionIdOrder == 0 && IsGreaterOrEqual(setVersion, _setVersion);
@@ -707,7 +707,9 @@ public override bool Equals(object obj)
             {
                 var other = obj as ElectionInfo;
 
-                return other != null && _setVersion == other.SetVersion && other.ElectionId == _electionId;
+                return other != null &&
+                    _setVersion == other.SetVersion &&
+                    object.Equals(_electionId, other.ElectionId);
             }
 
             private int Compare(ElectionId electionId)

tests/MongoDB.Driver.Core.Tests/Core/Clusters/ElectionIdTests.cs

@@ -48,7 +48,7 @@ public void Equals_should_return_false_if_any_field_is_not_equal()
         }
 
         [Fact]
-        public void Equals_should_return_true_if_all_fiels_are_equal()
+        public void Equals_should_return_true_if_all_fields_are_equal()
         {
             var subject1 = new ElectionId(ObjectId.Empty);
             var subject2 = new ElectionId(ObjectId.Empty);

tests/MongoDB.Driver.Core.Tests/Core/Clusters/MultiServerClusterTests.cs

@@ -685,6 +685,31 @@ public void Should_remove_a_server_whose_canonical_end_point_does_not_match_its_
             _capturedEvents.Any().Should().BeFalse();
         }
 
+        [Fact]
+        public void Should_not_invalidate_when_set_version_and_electionid_not_changed()
+        {
+            _settings = _settings.With(endPoints: new[] { _firstEndPoint, _secondEndPoint, _thirdEndPoint });
+            var setVersion = 1;
+            var objectId = ObjectId.GenerateNewId().ToString();
+
+            var subject = CreateSubject();
+            subject.Initialize();
+            _capturedEvents.Clear();
+
+            PublishDescription(subject, _firstEndPoint, ServerType.ReplicaSetPrimary, setVersion: setVersion, electionId: new ElectionId(ObjectId.Parse(objectId)));
+
+            var description = subject.Description;
+            description.State.Should().Be(ClusterState.Connected);
+            description.Type.Should().Be(ClusterType.ReplicaSet);
+            description.Servers.Should().BeEquivalentToWithComparer(GetDescriptions(_firstEndPoint, _secondEndPoint, _thirdEndPoint), _serverDescriptionComparer);
+
+            PublishDescription(subject, _firstEndPoint, ServerType.ReplicaSetPrimary, setVersion: setVersion, electionId: new ElectionId(ObjectId.Parse(objectId)));
+
+            _capturedEvents.Next().Should().BeOfType<SdamInformationEvent>();
+            _capturedEvents.Next().Should().BeOfType<ClusterDescriptionChangedEvent>();
+            _capturedEvents.Any().Should().BeFalse();
+        }
+
         [Fact]
         public void Should_not_remove_a_server_that_is_no_longer_in_a_secondaries_host_list()
         {