Fix tiny_map from_iter where one operation was being dropped

CHANGELOG.next.toml

@@ -11,6 +11,12 @@
 # meta = { "breaking" = false, "tada" = false, "bug" = false, "target" = "client | server | all"}
 # author = "rcoh"
 
+[[smithy-rs]]
+message = "Fix bug in AWS JSON 1.x routers where, if a service had more than 14 operations, the router was created without the route for the 15th operation."
+author = "thor-bjorgvinsson"
+references = ["smithy-rs#2733"]
+meta = { "breaking" = false, "tada" = false, "bug" = true, "target" ="server" }
+
 [[aws-sdk-rust]]
 message = "Remove native-tls and add a migration guide."
 author = "82marbag"

rust-runtime/aws-smithy-http-server/src/routing/tiny_map.rs

@@ -78,13 +78,13 @@ where
 
         // Populate the `Vec`
         while let Some((index, pair)) = iter.next() {
+            vec.push(pair);
+
             // If overflow `CUTOFF` then return a `HashMap` instead
             if index == CUTOFF {
                 let inner = TinyMapInner::HashMap(vec.into_iter().chain(iter.map(|(_, pair)| pair)).collect());
                 return TinyMap { inner };
             }
-
-            vec.push(pair);
         }
 
         TinyMap {
@@ -158,19 +158,25 @@ mod tests {
     #[test]
     fn get_small_success() {
         let tiny_map: TinyMap<_, _, CUTOFF> = SMALL_VALUES.into_iter().collect();
-        assert_eq!(tiny_map.get("a"), Some(&0))
+        SMALL_VALUES.into_iter().for_each(|(op, val)| {
+            assert_eq!(tiny_map.get(op), Some(&val));
+        });
     }
 
     #[test]
     fn get_medium_success() {
         let tiny_map: TinyMap<_, _, CUTOFF> = MEDIUM_VALUES.into_iter().collect();
-        assert_eq!(tiny_map.get("d"), Some(&3))
+        MEDIUM_VALUES.into_iter().for_each(|(op, val)| {
+            assert_eq!(tiny_map.get(op), Some(&val));
+        });
     }
 
     #[test]
     fn get_large_success() {
         let tiny_map: TinyMap<_, _, CUTOFF> = LARGE_VALUES.into_iter().collect();
-        assert_eq!(tiny_map.get("h"), Some(&7))
+        LARGE_VALUES.into_iter().for_each(|(op, val)| {
+            assert_eq!(tiny_map.get(op), Some(&val));
+        });
     }
 
     #[test]