CSHARP-2822: StartTransaction doesn't throw an exception when connected to Standalone nodes.

Author: rstam

README.md

@@ -130,6 +130,7 @@ Please see our [guidelines](CONTRIBUTING.md) for contributing to the driver.
 * Dow Liu                   [email protected]
 * Chuck Lu                  https://github.com/chucklu
 * Alex Lyman                [email protected]
+* Tomasz Masternak          https://github.com/tmasternak
 * John Murphy               https://github.com/jsmurphy
 * Alexander Nagy            [email protected]
 * Sridhar Nanjundeswaran    https://github.com/sridharn

src/MongoDB.Driver.Core/Core/Bindings/CoreSession.cs

@@ -469,9 +469,9 @@ private void EnsureTransactionsAreSupported()
             {
                 var serverType = connectedDataBearingServer.Type;
 
-                if(serverType == ServerType.Standalone || serverType == ServerType.Unknown)
+                if (serverType == ServerType.Standalone)
                 {
-                    throw new NotSupportedException("Transactions are supported only in sharded cluster of replica set deployments.");
+                    throw new NotSupportedException("Standalone servers do not support transactions.");
                 }
                 else if (serverType == ServerType.ShardRouter)
                 {

tests/MongoDB.Driver.Core.Tests/Core/Bindings/CoreSessionTests.cs

@@ -325,15 +325,14 @@ public void EnsureTransactionsAreSupported_should_throw_when_there_are_no_connec
         }
 
         [Theory]
-        [InlineData("NT")]
-        [InlineData("UT")]
-        [InlineData("PN")]
-        [InlineData("PN,ST")]
-        [InlineData("PT,SN")]
-        [InlineData("RN")]
-        [InlineData("RN,RT")]
-        [InlineData("RT,RN")]
-        public void EnsureTransactionsAreSupported_should_throw_when_any_connected_data_bearing_server_does_not_support_transactions(string scenarios)
+        [InlineData("NT", "Standalone servers do not support transactions.")]
+        [InlineData("PN", "Server version 3.99.99 does not support the Transactions feature.")]
+        [InlineData("PN,ST", "Server version 3.99.99 does not support the Transactions feature.")]
+        [InlineData("PT,SN", "Server version 3.99.99 does not support the Transactions feature.")]
+        [InlineData("RN", "Server version 4.1.5 does not support the ShardedTransactions feature.")]
+        [InlineData("RN,RT", "Server version 4.1.5 does not support the ShardedTransactions feature.")]
+        [InlineData("RT,RN", "Server version 4.1.5 does not support the ShardedTransactions feature.")]
+        public void EnsureTransactionsAreSupported_should_throw_when_any_connected_data_bearing_server_does_not_support_transactions(string scenarios, string expectedMesage)
         {
             var clusterId = new ClusterId(1);
             string unsupportedFeatureName = null;
@@ -360,11 +359,7 @@ public void EnsureTransactionsAreSupported_should_throw_when_any_connected_data_
             var exception = Record.Exception(() => subject.EnsureTransactionsAreSupported());
 
             var e = exception.Should().BeOfType<NotSupportedException>().Subject;
-            e.Message.Should().Match<string>(
-                s => s.Contains($"does not support the {unsupportedFeatureName} feature.") || 
-                     s.Contains("Transactions are supported only in sharded cluster of replica set deployments.") ||
-                     s.Contains("StartTransaction cannot determine if transactions are supported because there are no connected servers.")
-            );
+            e.Message.Should().Be(expectedMesage);
         }
 
         // private methods