CSHARP-2209: Fix race condition in ChangeStreamOperationTests

Author: rstam

tests/MongoDB.Driver.Core.Tests/Core/Operations/ChangeStreamOperationTests.cs

@@ -269,6 +269,7 @@ public void Execute_should_return_expected_results_for_drop_collection(
             var resultSerializer = new ChangeStreamDocumentSerializer<BsonDocument>(BsonDocumentSerializer.Instance);
             var messageEncoderSettings = new MessageEncoderSettings();
             var subject = new ChangeStreamOperation<ChangeStreamDocument<BsonDocument>>(_collectionNamespace, pipeline, resultSerializer, messageEncoderSettings);
+            EnsureDatabaseExists();
             DropCollection();
 
             using (var cursor = ExecuteOperation(subject, async))
@@ -298,6 +299,7 @@ public void Execute_should_return_expected_results_for_deletes(
             var resultSerializer = new ChangeStreamDocumentSerializer<BsonDocument>(BsonDocumentSerializer.Instance);
             var messageEncoderSettings = new MessageEncoderSettings();
             var subject = new ChangeStreamOperation<ChangeStreamDocument<BsonDocument>>(_collectionNamespace, pipeline, resultSerializer, messageEncoderSettings);
+            EnsureDatabaseExists();
             DropCollection();
 
             using (var cursor = ExecuteOperation(subject, async))
@@ -327,6 +329,7 @@ public void Execute_should_return_expected_results_for_inserts(
             var resultSerializer = new ChangeStreamDocumentSerializer<BsonDocument>(BsonDocumentSerializer.Instance);
             var messageEncoderSettings = new MessageEncoderSettings();
             var subject = new ChangeStreamOperation<ChangeStreamDocument<BsonDocument>>(_collectionNamespace, pipeline, resultSerializer, messageEncoderSettings);
+            EnsureDatabaseExists();
             DropCollection();
             Insert("{ _id : 1, x : 1 }");
 
@@ -361,6 +364,7 @@ public void Execute_should_return_expected_results_for_updates(
             {
                 FullDocument = fullDocument
             };
+            EnsureDatabaseExists();
             DropCollection();
 
             using (var cursor = ExecuteOperation(subject, async))

tests/MongoDB.Driver.Core.Tests/Core/Operations/DropDatabaseOperationTests.cs

@@ -185,12 +185,5 @@ public void WriteConcern_get_and_set_should_work(
 
             result.Should().BeSameAs(value);
         }
-
-        // helper methods
-        private void EnsureDatabaseExists()
-        {
-            var document = new BsonDocument();
-            Insert(document);
-        }
     }
 }

tests/MongoDB.Driver.Core.Tests/Core/Operations/OperationTestBase.cs

@@ -64,6 +64,12 @@ public virtual void Dispose()
             }
         }
 
+        protected void CreateCollection(CollectionNamespace collectionNamespace)
+        {
+            var operation = new CreateCollectionOperation(collectionNamespace, _messageEncoderSettings);
+            ExecuteOperation(operation);
+        }
+
         protected void Delete(BsonDocument filter)
         {
             var requests = new[] { new DeleteRequest(filter) };
@@ -90,7 +96,12 @@ protected Task DropDatabaseAsync()
 
         protected void DropCollection()
         {
-            var dropCollectionOperation = new DropCollectionOperation(_collectionNamespace, _messageEncoderSettings);
+            DropCollection(_collectionNamespace);
+        }
+
+        protected void DropCollection(CollectionNamespace collectionNamespace)
+        {
+            var dropCollectionOperation = new DropCollectionOperation(collectionNamespace, _messageEncoderSettings);
             ExecuteOperation(dropCollectionOperation);
         }
 
@@ -100,6 +111,19 @@ protected Task DropCollectionAsync()
             return ExecuteOperationAsync(dropCollectionOperation);
         }
 
+        protected void EnsureDatabaseExists()
+        {
+            var collectionName = $"EnsureDatabaseExists-{_databaseNamespace.DatabaseName}";
+            var collectionNamespace = new CollectionNamespace(_databaseNamespace, collectionName);
+            var filter = new BsonDocument("_id", 1);
+            var update = new BsonDocument("$set", new BsonDocument("x", 1));
+            var operation = new FindOneAndUpdateOperation<BsonDocument>(collectionNamespace, filter, update, BsonDocumentSerializer.Instance, new MessageEncoderSettings())
+            {
+                IsUpsert = true
+            };
+            ExecuteOperation(operation);
+        }
+
         protected TResult ExecuteOperation<TResult>(IReadOperation<TResult> operation)
         {
             using (var binding = CoreTestConfiguration.GetReadBinding(_session.Fork()))