Add more tests

Author: pablogsal

Lib/test/test_traceback.py

@@ -4343,6 +4343,57 @@ def __init__(self):
         actual = self.get_suggestion(Outer(), 'public_value')
         self.assertNotIn("Did you mean", actual)
 
+    def test_getattr_nested_limits_attribute_checks(self):
+        # Test that nested suggestions are limited to checking first 20 non-private attributes
+        class Inner:
+            def __init__(self):
+                self.target_value = 42
+
+        class Outer:
+            def __init__(self):
+                # Add many attributes before 'inner'
+                for i in range(25):
+                    setattr(self, f'attr_{i:02d}', i)
+                # Add the inner object after 20+ attributes
+                self.inner = Inner()
+
+        obj = Outer()
+        # Verify that 'inner' is indeed present but after position 20
+        attrs = [x for x in sorted(dir(obj)) if not x.startswith('_')]
+        inner_position = attrs.index('inner')
+        self.assertGreater(inner_position, 19, "inner should be after position 20 in sorted attributes")
+
+        # Should not suggest 'inner.target_value' because inner is beyond the first 20 attributes checked
+        actual = self.get_suggestion(obj, 'target_value')
+        self.assertNotIn("inner.target_value", actual)
+
+    def test_getattr_nested_returns_first_match_only(self):
+        # Test that only the first nested match is returned (not multiple)
+        class Inner1:
+            def __init__(self):
+                self.value = 1
+
+        class Inner2:
+            def __init__(self):
+                self.value = 2
+
+        class Inner3:
+            def __init__(self):
+                self.value = 3
+
+        class Outer:
+            def __init__(self):
+                # Multiple inner objects with same attribute
+                self.a_inner = Inner1()
+                self.b_inner = Inner2()
+                self.c_inner = Inner3()
+
+        # Should suggest only the first match (alphabetically)
+        actual = self.get_suggestion(Outer(), 'value')
+        self.assertIn("'a_inner.value'", actual)
+        # Verify it's a single suggestion, not multiple
+        self.assertEqual(actual.count("Did you mean"), 1)
+
     def make_module(self, code):
         tmpdir = Path(tempfile.mkdtemp())
         self.addCleanup(shutil.rmtree, tmpdir)

Lib/traceback.py

@@ -1603,13 +1603,13 @@ def _substitution_cost(ch_a, ch_b):
 
 def _check_for_nested_attribute(obj, wrong_name, attrs):
     """Check if any attribute of obj has the wrong_name as a nested attribute.
-    
+
     Returns the first nested attribute suggestion found, or None.
     Limited to checking 20 attributes and returning up to 5 suggestions.
     """
     nested_suggestions = []
     max_nested_suggestions = 5
-    
+
     # Check for nested attributes (only one level deep)
     attrs_to_check = [x for x in attrs if not x.startswith('_')][:20]  # Limit number of attributes to check
     for attr_name in attrs_to_check:
@@ -1622,7 +1622,7 @@ def _check_for_nested_attribute(obj, wrong_name, attrs):
                     break
         except:
             pass
-    
+
     return nested_suggestions[0] if nested_suggestions else None
 
 
@@ -1718,7 +1718,7 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
         if not suggestion or current_distance < best_distance:
             suggestion = possible_name
             best_distance = current_distance
-    
+
     # If no direct attribute match found, check for nested attributes
     if not suggestion and isinstance(exc_value, AttributeError):
         try:
@@ -1727,7 +1727,7 @@ def _compute_suggestion_error(exc_value, tb, wrong_name):
                 return nested_suggestion
         except:
             pass
-    
+
     return suggestion