Introduce internal consistency checks

osm2streets/src/intersection.rs

@@ -88,6 +88,20 @@ impl Intersection {
     pub fn is_map_edge(&self) -> bool {
         self.kind == IntersectionKind::MapEdge
     }
+
+    pub fn describe(&self) -> String {
+        let osm_ids = self
+            .osm_ids
+            .iter()
+            .map(|x| x.to_string())
+            .collect::<Vec<String>>()
+            .join(", ");
+        if osm_ids.is_empty() {
+            self.id.to_string()
+        } else {
+            format!("{} ({})", self.id, osm_ids)
+        }
+    }
 }
 
 impl StreetNetwork {

osm2streets/src/lib.rs

@@ -37,6 +37,7 @@ mod render;
 mod road;
 mod transform;
 mod types;
+mod validate;
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct StreetNetwork {

osm2streets/src/road.rs

@@ -497,6 +497,20 @@ impl Road {
     pub fn from_osm_way(&self, way: osm::WayID) -> bool {
         self.osm_ids.iter().any(|id| *id == way)
     }
+
+    pub fn describe(&self) -> String {
+        let osm_ids = self
+            .osm_ids
+            .iter()
+            .map(|x| x.to_string())
+            .collect::<Vec<String>>()
+            .join(", ");
+        if osm_ids.is_empty() {
+            self.id.to_string()
+        } else {
+            format!("{} ({})", self.id, osm_ids)
+        }
+    }
 }
 
 impl StreetNetwork {

osm2streets/src/validate.rs

@@ -0,0 +1,52 @@
+use crate::StreetNetwork;
+
+impl StreetNetwork {
+    /// Validates various things are true about the StreetNetwork, panicking if not.
+    pub fn check_invariants(&self) {
+        for r in self.roads.values() {
+            for i in r.endpoints() {
+                let i = &self.intersections[&i];
+                assert!(
+                    i.roads.contains(&r.id),
+                    "{} doesn't list {}",
+                    i.describe(),
+                    r.describe()
+                );
+            }
+            assert!(
+                !r.lane_specs_ltr.is_empty(),
+                "{} has no lanes",
+                r.describe()
+            );
+        }
+
+        for i in self.intersections.values() {
+            assert!(!i.roads.is_empty(), "{} has no roads", i.describe());
+
+            for r in &i.roads {
+                let r = &self.roads[r];
+                assert!(
+                    r.src_i == i.id || r.dst_i == i.id,
+                    "{} contains {}, which doesn't point to it",
+                    i.describe(),
+                    r.describe()
+                );
+            }
+
+            for (r1, r2) in &i.movements {
+                assert!(
+                    i.roads.contains(r1),
+                    "{} has a movement for the wrong road {}",
+                    i.describe(),
+                    r1
+                );
+                assert!(
+                    i.roads.contains(r2),
+                    "{} has a movement for the wrong road {}",
+                    i.describe(),
+                    r2
+                );
+            }
+        }
+    }
+}

tests/src/lib.rs

@@ -30,8 +30,10 @@ mod tests {
             MapConfig::default(),
             &mut timer,
         )?;
+        street_network.check_invariants();
         street_network
             .apply_transformations(Transformation::standard_for_clipped_areas(), &mut timer);
+        street_network.check_invariants();
         street_network.save_to_geojson(format!("{path}/geometry.json"))?;
 
         let road_network: RoadNetwork = street_network.into();