more tests

Author: KirillKurdyukov

src/Ydb.Sdk/src/Ado/Session/RetryableSession.cs

@@ -48,7 +48,7 @@ public void Dispose()
     {
     }
 
-    private static YdbException NotSupportedTransaction => new("Transactions are not supported in retryable sessions");
+    private static YdbException NotSupportedTransaction => new("Transactions are not supported in retryable session");
 }
 
 internal sealed class InMemoryServerStream : IServerStream<ExecuteQueryResponsePart>
@@ -108,14 +108,10 @@ public async Task<bool> MoveNextAsync(CancellationToken cancellationToken = defa
             }
         }, cancellationToken);
 
-        if (_index + 1 >= _responses.Count)
-            return false;
-        
-        _index++;
-        return true;
+        return ++_index < _responses.Count;
     }
 
-    public ExecuteQueryResponsePart Current => _responses is not null && _index < _responses.Count
+    public ExecuteQueryResponsePart Current => _responses is not null && _index >= 0 && _index < _responses.Count
         ? _responses[_index]
         : throw new InvalidOperationException("Enumeration has not started or has already finished");
 

src/Ydb.Sdk/test/Ydb.Sdk.Ado.Tests/Session/RetryableSessionTests.cs

@@ -99,9 +99,12 @@ public async Task MoveNextAsync_SucceedsOnThirdAttempt_StopsRetrying()
             null
         );
 
+        Assert.Throws<InvalidOperationException>(() => inMemoryStream.Current);
         var hasItem = await inMemoryStream.MoveNextAsync();
         Assert.True(hasItem);
         Assert.False(inMemoryStream.Current.Status.IsNotSuccess());
+        Assert.False(await inMemoryStream.MoveNextAsync());
+        Assert.Throws<InvalidOperationException>(() => inMemoryStream.Current);
 
         Assert.Equal(3, factory.SessionOpenedCount);
     }

src/Ydb.Sdk/test/Ydb.Sdk.Ado.Tests/YdbDataSourceTests.cs

@@ -246,4 +246,15 @@ public async Task ExecuteInTransactionAsync_WhenTLI_ThenRetriesUntilSuccess(int
             await new YdbCommand(ydbConnection) { CommandText = $"DROP TABLE {tableName}" }.ExecuteNonQueryAsync();
         }
     }
+
+    [Fact]
+    public async Task RetryableConnection_WhenOpenTransaction_Throws()
+    {
+        await using var ydbConnection = await _dataSource.OpenRetryableConnectionAsync();
+        await using var transaction = ydbConnection.BeginTransaction();
+
+        Assert.Equal("Transactions are not supported in retryable session",
+            (await Assert.ThrowsAsync<YdbException>(async () => await new YdbCommand(ydbConnection)
+                { CommandText = "SELECT 1" }.ExecuteScalarAsync())).Message);
+    }
 }