From c61abfa1e758675cc6aa9925e3e6468cf104eaa4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephan=20H=C3=BCgel?= <shugel@tcd.ie>
Date: Fri, 2 Dec 2022 10:03:05 +0000
Subject: [PATCH] Add preventative debug assert

See https://github.com/georust/geo/pull/941#issuecomment-1332305431
---
 geo/src/algorithm/simplify.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/geo/src/algorithm/simplify.rs b/geo/src/algorithm/simplify.rs
index 265d16fa4..1c49d9349 100644
--- a/geo/src/algorithm/simplify.rs
+++ b/geo/src/algorithm/simplify.rs
@@ -83,6 +83,7 @@ where
                 }
             },
         );
+    debug_assert_ne!(farthest_index, 0);
 
     if farthest_distance > *epsilon {
         // The farthest index was larger than epsilon, so we will recursively simplify subsegments
@@ -248,6 +249,18 @@ mod test {
     use crate::geo_types::coord;
     use crate::{line_string, polygon};
 
+    #[test]
+    fn recursion_test() {
+        let vec = [
+            coord! { x: 8.0, y: 100.0 },
+            coord! { x: 9.0, y: 100.0 },
+            coord! { x: 12.0, y: 100.0 },
+        ];
+        let compare = vec![coord! {x: 8.0, y: 100.0}, coord! {x: 12.0, y: 100.0}];
+        let simplified = rdp(vec.into_iter(), &1.0);
+        assert_eq!(simplified, compare);
+    }
+
     #[test]
     fn rdp_test() {
         let vec = vec![