public CoreStatGraph(IStatNodeFactory nodeFactory, PathDefinitionCollection paths)
 {
     _nodeFactory = nodeFactory;
     _paths       = paths;
 }
 private static CoreStatGraph CreateSut(
     IStatNodeFactory nodeFactory = null, PathDefinitionCollection paths = null) =>
 new CoreStatGraph(nodeFactory ?? Mock.Of <IStatNodeFactory>(), paths ?? CreatePathDefinitionCollection());