Running Lib/test/test_funcattrs.py directly fails

[Eclips4]

Bug report

Bug description:

eclips4@nixos ~/p/p/cpython (tests_for_ast_opt) [1]> ./python Lib/test/test_funcattrs.py
............F.....................
======================================================================
FAIL: test___builtins__ (__main__.FunctionPropertiesTest.test___builtins__)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/eclips4/programming/programming-languages/cpython/Lib/test/test_funcattrs.py", line 101, in test___builtins__
    self.assertIs(self.b.__builtins__, __builtins__)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: {'__name__': 'builtins', '__doc__': "Built-in functions, types, exceptions, and other objects.\n\nThis module provides direct access to all 'built-in'\nidentifiers of Python; for example, builtins.len is\nthe full name for the built-in function len().\n\nThis module is not normally accessed explicitly by most\napplications, but can be useful in modules that provide\nobjects with the same name as a built-in value, but in\nwhich the built-in of that name is also needed.", '__package__': '', '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': ModuleSpec(name='builtins', loader=<class '_frozen_importlib.BuiltinImporter'>, origin='built-in'), '__build_class__': <built-in function __build_class__>, '__import__': <built-in function __import__>, 'abs': <built-in function abs>, 'all': <built-in function all>, 'any': <built-in function any>, 'ascii': <built-in function ascii>, 'bin': <built-in function bin>, 'breakpoint': <built-in function breakpoint>, 'callable': <built-in function callable>, 'chr': <built-in function chr>, 'compile': <built-in function compile>, 'delattr': <built-in function delattr>, 'dir': <built-in function dir>, 'divmod': <built-in function divmod>, 'eval': <built-in function eval>, 'exec': <built-in function exec>, 'format': <built-in function format>, 'getattr': <built-in function getattr>, 'globals': <built-in function globals>, 'hasattr': <built-in function hasattr>, 'hash': <built-in function hash>, 'hex': <built-in function hex>, 'id': <built-in function id>, 'input': <built-in function input>, 'isinstance': <built-in function isinstance>, 'issubclass': <built-in function issubclass>, 'iter': <built-in function iter>, 'aiter': <built-in function aiter>, 'len': <built-in function len>, 'locals': <built-in function locals>, 'max': <built-in function max>, 'min': <built-in function min>, 'next': <built-in function next>, 'anext': <built-in function anext>, 'oct': <built-in function oct>, 'ord': <built-in function ord>, 'pow': <built-in function pow>, 'print': <built-in function print>, 'repr': <built-in function repr>, 'round': <built-in function round>, 'setattr': <built-in function setattr>, 'sorted': <built-in function sorted>, 'sum': <built-in function sum>, 'vars': <built-in function vars>, 'None': None, 'Ellipsis': Ellipsis, 'NotImplemented': NotImplemented, 'False': False, 'True': True, 'bool': <class 'bool'>, 'memoryview': <class 'memoryview'>, 'bytearray': <class 'bytearray'>, 'bytes': <class 'bytes'>, 'classmethod': <class 'classmethod'>, 'complex': <class 'complex'>, 'dict': <class 'dict'>, 'enumerate': <class 'enumerate'>, 'filter': <class 'filter'>, 'float': <class 'float'>, 'frozenset': <class 'frozenset'>, 'property': <class 'property'>, 'int': <class 'int'>, 'list': <class 'list'>, 'map': <class 'map'>, 'object': <class 'object'>, 'range': <class 'range'>, 'reversed': <class 'reversed'>, 'set': <class 'set'>, 'slice': <class 'slice'>, 'staticmethod': <class 'staticmethod'>, 'str': <class 'str'>, 'super': <class 'super'>, 'tuple': <class 'tuple'>, 'type': <class 'type'>, 'zip': <class 'zip'>, '__debug__': True, 'BaseException': <class 'BaseException'>, 'BaseExceptionGroup': <class 'BaseExceptionGroup'>, 'Exception': <class 'Exception'>, 'GeneratorExit': <class 'GeneratorExit'>, 'KeyboardInterrupt': <class 'KeyboardInterrupt'>, 'SystemExit': <class 'SystemExit'>, 'ArithmeticError': <class 'ArithmeticError'>, 'AssertionError': <class 'AssertionError'>, 'AttributeError': <class 'AttributeError'>, 'BufferError': <class 'BufferError'>, 'EOFError': <class 'EOFError'>, 'ImportError': <class 'ImportError'>, 'LookupError': <class 'LookupError'>, 'MemoryError': <class 'MemoryError'>, 'NameError': <class 'NameError'>, 'OSError': <class 'OSError'>, 'ReferenceError': <class 'ReferenceError'>, 'RuntimeError': <class 'RuntimeError'>, 'StopAsyncIteration': <class 'StopAsyncIteration'>, 'StopIteration': <class 'StopIteration'>, 'SyntaxError': <class 'SyntaxError'>, 'SystemError': <class 'SystemError'>, 'TypeError': <class 'TypeError'>, 'ValueError': <class 'ValueError'>, 'Warning': <class 'Warning'>, 'FloatingPointError': <class 'FloatingPointError'>, 'OverflowError': <class 'OverflowError'>, 'ZeroDivisionError': <class 'ZeroDivisionError'>, 'BytesWarning': <class 'BytesWarning'>, 'DeprecationWarning': <class 'DeprecationWarning'>, 'EncodingWarning': <class 'EncodingWarning'>, 'FutureWarning': <class 'FutureWarning'>, 'ImportWarning': <class 'ImportWarning'>, 'PendingDeprecationWarning': <class 'PendingDeprecationWarning'>, 'ResourceWarning': <class 'ResourceWarning'>, 'RuntimeWarning': <class 'RuntimeWarning'>, 'SyntaxWarning': <class 'SyntaxWarning'>, 'UnicodeWarning': <class 'UnicodeWarning'>, 'UserWarning': <class 'UserWarning'>, 'BlockingIOError': <class 'BlockingIOError'>, 'ChildProcessError': <class 'ChildProcessError'>, 'ConnectionError': <class 'ConnectionError'>, 'FileExistsError': <class 'FileExistsError'>, 'FileNotFoundError': <class 'FileNotFoundError'>, 'InterruptedError': <class 'InterruptedError'>, 'IsADirectoryError': <class 'IsADirectoryError'>, 'NotADirectoryError': <class 'NotADirectoryError'>, 'PermissionError': <class 'PermissionError'>, 'ProcessLookupError': <class 'ProcessLookupError'>, 'TimeoutError': <class 'TimeoutError'>, 'IndentationError': <class 'IndentationError'>, '_IncompleteInputError': <class '_IncompleteInputError'>, 'IndexError': <class 'IndexError'>, 'KeyError': <class 'KeyError'>, 'ModuleNotFoundError': <class 'ModuleNotFoundError'>, 'NotImplementedError': <class 'NotImplementedError'>, 'PythonFinalizationError': <class 'PythonFinalizationError'>, 'RecursionError': <class 'RecursionError'>, 'UnboundLocalError': <class 'UnboundLocalError'>, 'UnicodeError': <class 'UnicodeError'>, 'BrokenPipeError': <class 'BrokenPipeError'>, 'ConnectionAbortedError': <class 'ConnectionAbortedError'>, 'ConnectionRefusedError': <class 'ConnectionRefusedError'>, 'ConnectionResetError': <class 'ConnectionResetError'>, 'TabError': <class 'TabError'>, 'UnicodeDecodeError': <class 'UnicodeDecodeError'>, 'UnicodeEncodeError': <class 'UnicodeEncodeError'>, 'UnicodeTranslateError': <class 'UnicodeTranslateError'>, 'ExceptionGroup': <class 'ExceptionGroup'>, 'EnvironmentError': <class 'OSError'>, 'IOError': <class 'OSError'>, 'open': <built-in function open>, 'quit': Use quit() or Ctrl-D (i.e. EOF) to exit, 'exit': Use exit() or Ctrl-D (i.e. EOF) to exit, 'copyright': Copyright (c) 2001-2024 Python Software Foundation.
All Rights Reserved.

Copyright (c) 2000 BeOpen.com.
All Rights Reserved.

Copyright (c) 1995-2001 Corporation for National Research Initiatives.
All Rights Reserved.

Copyright (c) 1991-1995 Stichting Mathematisch Centrum, Amsterdam.
All Rights Reserved., 'credits':     Thanks to CWI, CNRI, BeOpen.com, Zope Corporation and a cast of thousands
    for supporting Python development.  See www.python.org for more information., 'license': Type license() to see the full license text, 'help': Type help() for interactive help, or help(object) for help about object.} is not <module 'builtins' (built-in)>

----------------------------------------------------------------------
Ran 34 tests in 0.007s

FAILED (failures=1)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-122864: Fix a test_funcattrs.test___builtins__ when executing directly #124845
• [3.13] gh-122864: Fix a test_funcattrs.test___builtins__ when executing directly (GH-124845) #124884
• [3.12] gh-122864: Fix a test_funcattrs.test___builtins__ when executing directly (GH-124845) #124885

[Eclips4]

The culprit is the test___builtins__ which has this line:
self.assertIs(self.b.__builtins__, __builtins__), which translates to

def b(): pass

assert b.__builtins__ is __builtins__

I'm wondering why running this test using ./python -m test doesn't failing.

[picnixz]

Could be something where there is an exec/eval polluting a namespace? I don't have access to sources so I cannot even check nut might be worth changing the name of the object being tested, or look at whether builtins is reloaded at some point?

[mbyrnepr2]

I think this part of the docs explains the behaviour:

By default, when in the __main__ module, __builtins__ is the built-in module [builtins]; when in any other module, __builtins__ is an alias for the dictionary of the builtins module itself.

./python.exe -m test.test_funcattrs:

markbyrne@Marks-Air-2 cpython % ./python.exe -m test.test_funcattrs
> /Users/markbyrne/programming/cpython/Lib/test/test_funcattrs.py(101)test___builtins__()
-> breakpoint()
(Pdb) __name__
'__main__'
(Pdb) __builtins__
<module 'builtins' (built-in)>
(Pdb) __builtins__.__dict__ is __builtins__
False
(Pdb)

./python.exe -m test:

> /Users/markbyrne/programming/cpython/Lib/test/test_funcattrs.py(101)test___builtins__()
(Pdb) __name__
'test.test_funcattrs'
(Pdb) import builtins
(Pdb) builtins.__dict__ is __builtins__
True
(Pdb)

So, one way forward could be to update the test to first check if we are inside __main__ and update the value of __builtins__ accordingly with a basic if/else.

Edit: However, it isn't clear why self.b.__builtins__ is the same value in each scenario. I understood from the Changelog that it should be equal to the value of globals()["__builtins__"] which is different in each scenario:
Functions have a new __builtins__ attribute which is used to look for builtin symbols when a function is executed, instead of looking into __globals__['__builtins__']. The attribute is initialized from __globals__["__builtins__"] if it exists, else from the current builtins.

Edit 2: I gather from https://bugs.python.org/issue42990 that func.__builtins__ is builtins.__dict__. The following could work?

--- a/Lib/test/test_funcattrs.py
+++ b/Lib/test/test_funcattrs.py
@@ -98,7 +98,23 @@ def test___globals__(self):
                              (AttributeError, TypeError))

     def test___builtins__(self):
-        self.assertIs(self.b.__builtins__, __builtins__)
+        if __name__ == "__main__":
+            # `func.__builtins__` is `builtins.__dict__`.
+            # See:https://bugs.python.org/issue42990
+
+            # When this test is run by executing the current module,
+            # `__builtins__` is the built-in module `builtins`.
+
+            # When this test is run from another module, `__builtins__` is
+            # `builtins.__dict__`
+            # See: https://docs.python.org/3/reference/executionmodel.html#builtins-and-restricted-execution
+
+            import builtins
+            builtins_dict = builtins.__dict__
+        else:
+            builtins_dict = __builtins__
+
+        self.assertIs(self.b.__builtins__, builtins_dict)
         self.cannot_set_attr(self.b, '__builtins__', 2,
                              (AttributeError, TypeError))

@@ -108,7 +124,7 @@ def func(s): return len(s)
         ns = {}
         func2 = type(func)(func.__code__, ns)
         self.assertIs(func2.__globals__, ns)
-        self.assertIs(func2.__builtins__, __builtins__)
+        self.assertIs(func2.__builtins__, builtins_dict)

         # Make sure that the function actually works.

[Eclips4]

Thanks @mbyrnepr2!