CSHARP-5545: Fix flaky test .TransactionsConvenientApi_testCase__transaction-options.json_withTransaction_explicit_transaction_options_override_client_options (#1654)

Author: sanych-sun

src/MongoDB.Driver/Core/Clusters/ServerSelectors/WritableServerSelector.cs

@@ -79,6 +79,7 @@ public IEnumerable<ServerDescription> SelectServers(ClusterDescription cluster,
             var serversList = servers.ToList(); // avoid multiple enumeration
             if (CanUseSecondaries(cluster, serversList))
             {
+                _mayUseSecondary.EffectiveReadPreference = _mayUseSecondary.ReadPreference;
                 var readPreferenceSelector = new ReadPreferenceServerSelector(_mayUseSecondary.ReadPreference);
                 return readPreferenceSelector.SelectServers(cluster, serversList);
             }

tests/MongoDB.Driver.Tests/UnifiedTestOperations/UnifiedEntityMap.cs

@@ -17,6 +17,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using MongoDB.Bson;
 using MongoDB.Driver.Authentication.Oidc;
@@ -38,15 +39,16 @@ namespace MongoDB.Driver.Tests.UnifiedTestOperations
     public sealed class UnifiedEntityMap : IDisposable
     {
         #region static
-        public static UnifiedEntityMap Create(Dictionary<string, IEventFormatter> eventFormatters, LoggingSettings loggingSettings, bool async)
-            => new(eventFormatters, loggingSettings, async);
+        public static UnifiedEntityMap Create(Dictionary<string, IEventFormatter> eventFormatters, LoggingSettings loggingSettings, bool async, BsonDocument lastKnownClusterTime)
+            => new(eventFormatters, loggingSettings, async, lastKnownClusterTime);
 
         #endregion
 
         // private fields
         private readonly bool _async;
         private readonly Dictionary<string, IEventFormatter> _eventFormatters;
         private readonly LoggingSettings _loggingSettings;
+        private readonly BsonDocument _lastKnownClusterTime;
 
         private readonly Dictionary<string, IGridFSBucket> _buckets = new();
         private readonly Dictionary<string, IEnumerator<ChangeStreamDocument<BsonDocument>>> _changeStreams = new();
@@ -73,11 +75,13 @@ public static UnifiedEntityMap Create(Dictionary<string, IEventFormatter> eventF
         private UnifiedEntityMap(
             Dictionary<string, IEventFormatter> eventFormatters,
             LoggingSettings loggingSettings,
-            bool async)
+            bool async,
+            BsonDocument lastKnownClusterTime)
         {
             _eventFormatters = eventFormatters ?? new();
             _loggingSettings = loggingSettings;
             _async = async;
+            _lastKnownClusterTime = lastKnownClusterTime;
         }
 
         // public properties
@@ -1011,6 +1015,10 @@ private IClientSessionHandle CreateSession(BsonDocument entity, Dictionary<strin
             }
 
             var session = client.StartSession(options);
+            if (_lastKnownClusterTime != null)
+            {
+                session.WrappedCoreSession.AdvanceClusterTime(_lastKnownClusterTime);
+            }
 
             return session;
         }

tests/MongoDB.Driver.Tests/UnifiedTestOperations/UnifiedTestRunner.cs

@@ -132,14 +132,10 @@ public void Run(
                 KillOpenTransactions(DriverTestConfiguration.Client);
             }
 
-            _entityMap = UnifiedEntityMap.Create(_eventFormatters, _loggingService.LoggingSettings, async);
+            BsonDocument lastKnownClusterTime = AddInitialData(DriverTestConfiguration.Client, initialData);
+            _entityMap = UnifiedEntityMap.Create(_eventFormatters, _loggingService.LoggingSettings, async, lastKnownClusterTime);
             _entityMap.AddRange(entities);
 
-            if (initialData != null)
-            {
-                AddInitialData(DriverTestConfiguration.Client, initialData, _entityMap);
-            }
-
             foreach (var operation in operations)
             {
                 var cancellationToken = CancellationToken.None;
@@ -181,45 +177,36 @@ public void Dispose()
         }
 
         // private methods
-        private void AddInitialData(IMongoClient client, BsonArray initialData, UnifiedEntityMap entityMap)
+        private BsonDocument AddInitialData(IMongoClient client, BsonArray initialData)
         {
-            var mongoCollectionSettings = new MongoCollectionSettings();
-
-            var writeConcern = WriteConcern.WMajority;
-            if (DriverTestConfiguration.IsReplicaSet(client))
+            if (initialData == null)
             {
-                // Makes server to wait for ack from all data nodes to make sure the test data availability before running the test itself.
-                // It's limited to replica set only because there is no simple way to calculate proper w for sharded cluster.
-                var dataBearingServersCount = DriverTestConfiguration.GetReplicaSetNumberOfDataBearingMembers(client);
-                writeConcern = WriteConcern.Acknowledged.With(w: dataBearingServersCount, journal:true);
+                return null;
             }
 
-            BsonDocument serverTime = null;
+            BsonDocument lastKnownClusterTime = null;
             foreach (var dataItem in initialData)
             {
                 var collectionName = dataItem["collectionName"].AsString;
                 var databaseName = dataItem["databaseName"].AsString;
                 var documents = dataItem["documents"].AsBsonArray.Cast<BsonDocument>().ToList();
 
-                var database = client.GetDatabase(databaseName).WithWriteConcern(writeConcern);
-                var collection = database.GetCollection<BsonDocument>(collectionName, mongoCollectionSettings);
+                var database = client.GetDatabase(databaseName).WithWriteConcern(WriteConcern.WMajority);
 
                 _logger.LogDebug("Dropping {0}", collectionName);
-                var session = client.StartSession();
+                using var session = client.StartSession();
                 database.DropCollection(session, collectionName);
+                database.CreateCollection(session, collectionName);
                 if (documents.Any())
                 {
+                    var collection = database.GetCollection<BsonDocument>(collectionName);
                     collection.InsertMany(session, documents);
                 }
-                else
-                {
-                    database.CreateCollection(session, collectionName);
-                }
 
-                serverTime = session.ClusterTime;
+                lastKnownClusterTime = session.ClusterTime;
             }
 
-            entityMap.AdjustSessionsClusterTime(serverTime);
+            return lastKnownClusterTime;
         }
 
         private void AssertEvents(BsonArray eventItems, UnifiedEntityMap entityMap)