public void graphs_which_contain_circular_references_are_not_supported()
{
var graph = new SimpleType();
// Root to self.
graph.Value = graph;
Assert.Throws<SerializationException>(() => Write(graph));
// Descendent to root.
graph.Value = new SimpleType { Value = graph };
Assert.Throws<SerializationException>(() => Write(graph));
// Descendent to self.
graph.Value = new SimpleType();
graph.Value.Value = graph.Value;
Assert.Throws<SerializationException>(() => Write(graph));
// Descendent to parent.
graph.Value = new SimpleType { Value = graph.Value };
Assert.Throws<SerializationException>(() => Write(graph));
}