Harden mapping key display blank/control fallback

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

Author: cursoragent

hyperbrowser/mapping_utils.py

@@ -12,6 +12,10 @@ def safe_key_display_for_error(
         key_text = key_display(key)
         if not is_plain_string(key_text):
             raise TypeError("mapping key display must be a string")
+        if not key_text.strip():
+            raise ValueError("mapping key display must not be blank")
+        if any(ord(character) < 32 or ord(character) == 127 for character in key_text):
+            raise ValueError("mapping key display must not contain control characters")
         return key_text
     except Exception:
         return "<unreadable key>"

tests/test_mapping_utils.py

@@ -163,6 +163,26 @@ class _DisplayString(str):
     )
 
 
+def test_safe_key_display_for_error_returns_unreadable_key_for_blank_display_values():
+    assert (
+        safe_key_display_for_error(
+            "field",
+            key_display=lambda key: f"  {key[:0]}  ",
+        )
+        == "<unreadable key>"
+    )
+
+
+def test_safe_key_display_for_error_returns_unreadable_key_for_control_display_values():
+    assert (
+        safe_key_display_for_error(
+            "field",
+            key_display=lambda key: f"{key}\n\t",
+        )
+        == "<unreadable key>"
+    )
+
+
 def test_read_string_mapping_keys_returns_string_keys():
     assert read_string_mapping_keys(
         {"a": 1, "b": 2},