Wrap header mapping iteration failures

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

Author: cursoragent

hyperbrowser/header_utils.py

@@ -8,6 +8,17 @@
 _MAX_HEADER_NAME_LENGTH = 256
 
 
+def _read_header_items(
+    headers: Mapping[str, str], *, mapping_error_message: str
+) -> list[tuple[object, object]]:
+    try:
+        return list(headers.items())
+    except HyperbrowserError:
+        raise
+    except Exception as exc:
+        raise HyperbrowserError(mapping_error_message, original_error=exc) from exc
+
+
 def normalize_headers(
     headers: Optional[Mapping[str, str]],
     *,
@@ -22,7 +33,9 @@ def normalize_headers(
     effective_pair_error_message = pair_error_message or mapping_error_message
     normalized_headers: Dict[str, str] = {}
     seen_header_names = set()
-    for key, value in headers.items():
+    for key, value in _read_header_items(
+        headers, mapping_error_message=mapping_error_message
+    ):
         if not isinstance(key, str) or not isinstance(value, str):
             raise HyperbrowserError(effective_pair_error_message)
         normalized_key = key.strip()

tests/test_header_utils.py

@@ -8,6 +8,11 @@
 )
 
 
+class _BrokenHeadersMapping(dict):
+    def items(self):
+        raise RuntimeError("broken header iteration")
+
+
 def test_normalize_headers_trims_header_names():
     headers = normalize_headers(
         {"  X-Correlation-Id  ": "abc123"},
@@ -161,3 +166,28 @@ def test_merge_headers_rejects_duplicate_base_header_names_case_insensitive():
             None,
             mapping_error_message="headers must be a mapping of string pairs",
         )
+
+
+def test_normalize_headers_wraps_mapping_iteration_failures():
+    with pytest.raises(
+        HyperbrowserError, match="headers must be a mapping of string pairs"
+    ) as exc_info:
+        normalize_headers(
+            _BrokenHeadersMapping({"X-Trace-Id": "abc123"}),
+            mapping_error_message="headers must be a mapping of string pairs",
+        )
+
+    assert exc_info.value.original_error is not None
+
+
+def test_merge_headers_wraps_override_mapping_iteration_failures():
+    with pytest.raises(
+        HyperbrowserError, match="headers must be a mapping of string pairs"
+    ) as exc_info:
+        merge_headers(
+            {"X-Trace-Id": "abc123"},
+            _BrokenHeadersMapping({"X-Correlation-Id": "corr-1"}),
+            mapping_error_message="headers must be a mapping of string pairs",
+        )
+
+    assert exc_info.value.original_error is not None