public IEdge Build()
{
IEdge edge = Substitute.For <IEdge>();
edge.ChildNode.Returns(ChildNode);
if (ChildExtractor != null)
{
edge.ExtractChildValue(Arg.Any <T>())
.Returns(args => ChildExtractor((T)args[0]));
}
SetupSetChildValue(edge);
return(edge);
}