Require concrete string path normalization outputs in URL builder

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

hyperbrowser/client/base.py

@@ -150,20 +150,22 @@ def _build_url(self, path: str) -> str:
             raise HyperbrowserError("path must be a string")
         try:
             stripped_path = path.strip()
-            if not isinstance(stripped_path, str):
+            if type(stripped_path) is not str:
                 raise TypeError("normalized path must be a string")
+            has_surrounding_whitespace = stripped_path != path
+            is_empty_path = len(stripped_path) == 0
         except HyperbrowserError:
             raise
         except Exception as exc:
             raise HyperbrowserError(
                 "Failed to normalize path",
                 original_error=exc,
             ) from exc
-        if stripped_path != path:
+        if has_surrounding_whitespace:
             raise HyperbrowserError(
                 "path must not contain leading or trailing whitespace"
             )
-        if not stripped_path:
+        if is_empty_path:
             raise HyperbrowserError("path must not be empty")
         if "\\" in stripped_path:
             raise HyperbrowserError("path must not contain backslashes")

tests/test_url_building.py

@@ -401,6 +401,25 @@ def strip(self, chars=None):  # type: ignore[override]
         client.close()
 
 
+def test_client_build_url_wraps_string_subclass_path_strip_results():
+    client = Hyperbrowser(config=ClientConfig(api_key="test-key"))
+    try:
+        class _BrokenPath(str):
+            class _NormalizedPath(str):
+                pass
+
+            def strip(self, chars=None):  # type: ignore[override]
+                _ = chars
+                return self._NormalizedPath("/session")
+
+        with pytest.raises(HyperbrowserError, match="Failed to normalize path") as exc_info:
+            client._build_url(_BrokenPath("/session"))
+
+        assert isinstance(exc_info.value.original_error, TypeError)
+    finally:
+        client.close()
+
+
 def test_client_build_url_allows_query_values_containing_absolute_urls():
     client = Hyperbrowser(config=ClientConfig(api_key="test-key"))
     try: