fix: get codepoint range rather than bytes

Author: melbourne2991

src/constructor_parser.rs

@@ -167,11 +167,13 @@ impl<'a> ConstructorStringParser<'a> {
     assert!(self.token_index < self.token_list.len());
     let token = &self.token_list[self.token_index];
     let component_start_index = self.get_safe_token(self.component_start).index;
+
     self
       .input
-      .get(component_start_index..token.index) // TODO: check & codepoint
-      .unwrap()
-      .to_string()
+      .chars()
+      .skip(component_start_index)
+      .take(token.index - component_start_index)
+      .collect()
   }
 
   // Ref: https://wicg.github.io/urlpattern/#rewind-and-set-state

src/testdata/urlpatterntestdata.json

@@ -2721,5 +2721,15 @@
     "expected_match": {
       "pathname": { "input": "/bazbar", "groups": { "foo": "baz" }}
     }
+  },
+  {
+    "pattern": [":café://:foo"],
+    "exactly_empty_components": [ "username", "password", "port", "search",
+    "hash" ],
+    "expected_obj": {
+      "protocol": ":café",
+      "hostname": ":foo",
+      "pathname": "/"
+    }
   }
 ]