some checks on self interctin

geo/src/algorithm/relate/geomgraph/geometry_graph.rs

@@ -61,7 +61,7 @@ where
         (self.tree.as_ref().unwrap(), edges)
     }
 
-    fn update_tree(&mut self) {
+    pub(crate) fn update_tree(&mut self) {
         if self.tree.is_none() {
             self.tree = Some(self.build_tree());
         }

geo/src/algorithm/relate/geomgraph/index/prepared_geometry.rs

@@ -158,6 +158,7 @@ mod conversions {
     impl<'a, F: GeoFloat> From<GeometryCow<'a, F>> for PreparedGeometry<'a, F> {
         fn from(geometry: GeometryCow<'a, F>) -> Self {
             let mut geometry_graph = GeometryGraph::new(0, geometry);
+            geometry_graph.update_tree(); // TODO: maybe unecessary
 
             // TODO: don't pass in line intersector here - in theory we'll want pluggable line intersectors
             // and the type (Robust) shouldn't be hard coded here.

geo/src/algorithm/relate/geomgraph/index/simple_edge_set_intersector.rs

@@ -50,9 +50,11 @@ impl<F: GeoFloat> EdgeSetIntersector<F> for SimpleEdgeSetIntersector {
         segment_intersector: &mut SegmentIntersector<F>,
     ) {
         let edges = graph.edges_mut();
+        let mut checks = 0;
         for i in 0..edges.len() {
             let (e0, e1) = edges.split_at_mut(i + 1);
             let (e0, edge0) = e0.split_at_mut(i);
+            assert_eq!(edge0.len(), 1);
             let edge0 = &mut edge0[0];
 
             if check_for_self_intersecting_edges {
@@ -61,8 +63,12 @@ impl<F: GeoFloat> EdgeSetIntersector<F> for SimpleEdgeSetIntersector {
 
             for edge1 in e0.iter_mut().chain(e1) {
                 self.compute_intersects(edge0, edge1, segment_intersector);
+                checks += 1;
             }
         }
+
+        println!("checks: {}", checks);
+        assert_eq!(checks, edges.len()*edges.len());
     }
 
     fn compute_intersections_between_sets<'a>(