RavenDb connectionstring memory=true not working

I'm trying to setup unit tests for a Web Api app with RavenDb.Client. The app is using a RavenDb server running as a service and works just fine.

In my test project I've set the connection string to Memory=True, but the tests throws an exception saying that "memory" is an unknown option.

What am I doing wrong?

  <connectionStrings>
    <add name="RavenDbConnectionString" connectionString="memory=1"/>
  </connectionStrings>


IDocumentStore store = new DocumentStore()
            {
                ConnectionStringName = "RavenDbConnectionString"
            }.Initialize();