add more test cases

Author: KevinRK29

mypy/errors.py

@@ -838,6 +838,7 @@ def is_ignored_error_code(self, line: int, code: ErrorCode) -> bool:
         if line not in ignores:
             return False
         if not ignores[line]:
+            # Empty list means that we ignore all errors
             return True
         return (
             code.code in ignores[line]

mypy/semanal.py

@@ -7533,8 +7533,8 @@ def _get_names_in_scope(self) -> set[str]:
         names.update(self.globals.keys())
 
         b = self.globals.get("__builtins__", None)
-        if b and isinstance(b.node, MypyFile):
-            # Only include public builtins (not _private ones)
+        if b:
+            assert isinstance(b.node, MypyFile)
             for builtin_name in b.node.names.keys():
                 if not (len(builtin_name) > 1 and builtin_name[0] == "_" and builtin_name[1] != "_"):
                     names.add(builtin_name)

test-data/unit/check-errorcodes.test

@@ -73,6 +73,19 @@ def some_function(x: int) -> int:
 x = lenn  # E: Name "lenn" is not defined; did you mean "len"?  [name-defined]
 [builtins fixtures/len.pyi]
 
+[case testErrorCodeUndefinedNameSuggestionClassMethod]
+class Foo:
+    class_attr = 10
+    def method(self) -> None:
+        x = class_atr  # E: Name "class_atr" is not defined  [name-defined]
+[builtins fixtures/module.pyi]
+
+[case testErrorCodeUndefinedNameSuggestionMultiple]
+total_count = 1
+total_counts = 2
+x = total_countt  # E: Name "total_countt" is not defined; did you mean "total_count" or "total_counts"?  [name-defined]
+[builtins fixtures/module.pyi]
+
 [case testErrorCodeUndefinedNameSuggestionIgnored]
 my_variable = 42
 x = my_variabel  # type: ignore[name-defined]