Summary

MongoDbRunner.Start on singleNodeReplSet:true mode throws
StartTransaction cannot determine if transactions are supported because there are no connected servers when trying to start the transaction.

But when I'm running this test on the Mongo2Go project it passes.

Steps:

var runner= MongoDbRunner.Start(singleNodeReplSet: true);
var client = new MongoClient(this.runner.ConnectionString);
var database = client.GetDatabase("testdb");
var session = client.StartSession();
session.StartTransaction(); <--------- The Exception part

Exception

System.NotSupportedException : StartTransaction cannot determine if transactions are supported because there are no connected servers.
  Stack Trace:
     at MongoDB.Driver.Core.Bindings.CoreSession.EnsureTransactionsAreSupported()
   at MongoDB.Driver.Core.Bindings.CoreSession.EnsureStartTransactionCanBeCalled()
   at MongoDB.Driver.Core.Bindings.CoreSession.StartTransaction(TransactionOptions transactionOptions)
   at MongoDB.Driver.ClientSessionHandle.StartTransaction(TransactionOptions transactionOptions)

Environment

.NET Core SDK (reflecting any global.json):
Version: 3.1.100
Commit: cd82f021f4

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.15
OS Platform: Darwin
RID: osx.10.15-x64
Base Path: /usr/local/share/dotnet/sdk/3.1.100/

Host (useful for support):
Version: 3.1.0
Commit: 65f04fb6db

.NET Core SDKs installed:
3.0.100 [/usr/local/share/dotnet/sdk]
3.1.100 [/usr/local/share/dotnet/sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.App 3.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.13 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Also, I'm using xunit as my TestFramework.