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cpython/Lib/test/test_frame.py

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import copy
import gc
import operator
import re
import sys
import textwrap
import threading
import types
import unittest
import weakref
try:
import _testcapi
except ImportError:
_testcapi = None
from test import support
from test.support import import_helper, threading_helper, Py_GIL_DISABLED
from test.support.script_helper import assert_python_ok
class ClearTest(unittest.TestCase):
"""
Tests for frame.clear().
"""
def inner(self, x=5, **kwargs):
1/0
def outer(self, **kwargs):
try:
self.inner(**kwargs)
except ZeroDivisionError as e:
exc = e
return exc
def clear_traceback_frames(self, tb):
"""
Clear all frames in a traceback.
"""
while tb is not None:
tb.tb_frame.clear()
tb = tb.tb_next
def test_clear_locals(self):
class C:
pass
c = C()
wr = weakref.ref(c)
exc = self.outer(c=c)
del c
support.gc_collect()
# A reference to c is held through the frames
self.assertIsNot(None, wr())
self.clear_traceback_frames(exc.__traceback__)
support.gc_collect()
# The reference was released by .clear()
self.assertIs(None, wr())
def test_clear_locals_after_f_locals_access(self):
# see gh-113939
class C:
pass
wr = None
def inner():
nonlocal wr
c = C()
wr = weakref.ref(c)
1/0
try:
inner()
except ZeroDivisionError as exc:
support.gc_collect()
self.assertIsNotNone(wr())
exc.__traceback__.tb_next.tb_frame.clear()
support.gc_collect()
self.assertIsNone(wr())
def test_clear_does_not_clear_specials(self):
class C:
pass
c = C()
exc = self.outer(c=c)
del c
f = exc.__traceback__.tb_frame
f.clear()
self.assertIsNot(f.f_code, None)
self.assertIsNot(f.f_locals, None)
self.assertIsNot(f.f_builtins, None)
self.assertIsNot(f.f_globals, None)
def test_clear_generator(self):
endly = False
def g():
nonlocal endly
try:
yield
self.inner()
finally:
endly = True
gen = g()
next(gen)
self.assertFalse(endly)
# Cannot clear a suspended frame
with self.assertRaisesRegex(RuntimeError, r'suspended frame'):
gen.gi_frame.clear()
self.assertFalse(endly)
def test_clear_executing(self):
# Attempting to clear an executing frame is forbidden.
try:
1/0
except ZeroDivisionError as e:
f = e.__traceback__.tb_frame
with self.assertRaises(RuntimeError):
f.clear()
with self.assertRaises(RuntimeError):
f.f_back.clear()
def test_clear_executing_generator(self):
# Attempting to clear an executing generator frame is forbidden.
endly = False
def g():
nonlocal endly
try:
1/0
except ZeroDivisionError as e:
f = e.__traceback__.tb_frame
with self.assertRaises(RuntimeError):
f.clear()
with self.assertRaises(RuntimeError):
f.f_back.clear()
yield f
finally:
endly = True
gen = g()
f = next(gen)
self.assertFalse(endly)
# Cannot clear a suspended frame
with self.assertRaisesRegex(RuntimeError, 'suspended frame'):
f.clear()
self.assertFalse(endly)
def test_lineno_with_tracing(self):
def record_line():
f = sys._getframe(1)
lines.append(f.f_lineno-f.f_code.co_firstlineno)
def test(trace):
record_line()
if trace:
sys._getframe(0).f_trace = True
record_line()
record_line()
expected_lines = [1, 4, 5]
lines = []
test(False)
self.assertEqual(lines, expected_lines)
lines = []
test(True)
self.assertEqual(lines, expected_lines)
@support.cpython_only
def test_clear_refcycles(self):
# .clear() doesn't leave any refcycle behind
with support.disable_gc():
class C:
pass
c = C()
wr = weakref.ref(c)
exc = self.outer(c=c)
del c
self.assertIsNot(None, wr())
self.clear_traceback_frames(exc.__traceback__)
self.assertIs(None, wr())
class FrameAttrsTest(unittest.TestCase):
def make_frames(self):
def outer():
x = 5
y = 6
def inner():
z = x + 2
1/0
t = 9
return inner()
try:
outer()
except ZeroDivisionError as e:
tb = e.__traceback__
frames = []
while tb:
frames.append(tb.tb_frame)
tb = tb.tb_next
return frames
def test_clear_locals(self):
# Test f_locals after clear() (issue #21897)
f, outer, inner = self.make_frames()
outer.clear()
inner.clear()
self.assertEqual(outer.f_locals, {})
self.assertEqual(inner.f_locals, {})
def test_locals_clear_locals(self):
# Test f_locals before and after clear() (to exercise caching)
f, outer, inner = self.make_frames()
self.assertNotEqual(outer.f_locals, {})
self.assertNotEqual(inner.f_locals, {})
outer.clear()
inner.clear()
self.assertEqual(outer.f_locals, {})
self.assertEqual(inner.f_locals, {})
def test_f_lineno_del_segfault(self):
f, _, _ = self.make_frames()
with self.assertRaises(AttributeError):
del f.f_lineno
class ReprTest(unittest.TestCase):
"""
Tests for repr(frame).
"""
def test_repr(self):
def outer():
x = 5
y = 6
def inner():
z = x + 2
1/0
t = 9
return inner()
offset = outer.__code__.co_firstlineno
try:
outer()
except ZeroDivisionError as e:
tb = e.__traceback__
frames = []
while tb:
frames.append(tb.tb_frame)
tb = tb.tb_next
else:
self.fail("should have raised")
f_this, f_outer, f_inner = frames
file_repr = re.escape(repr(__file__))
self.assertRegex(repr(f_this),
r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code test_repr>$"
% (file_repr, offset + 23))
self.assertRegex(repr(f_outer),
r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code outer>$"
% (file_repr, offset + 7))
self.assertRegex(repr(f_inner),
r"^<frame at 0x[0-9a-fA-F]+, file %s, line %d, code inner>$"
% (file_repr, offset + 5))
class TestFrameLocals(unittest.TestCase):
def test_scope(self):
class A:
x = 1
sys._getframe().f_locals['x'] = 2
sys._getframe().f_locals['y'] = 2
self.assertEqual(A.x, 2)
self.assertEqual(A.y, 2)
def f():
x = 1
sys._getframe().f_locals['x'] = 2
sys._getframe().f_locals['y'] = 2
self.assertEqual(x, 2)
self.assertEqual(locals()['y'], 2)
f()
def test_closure(self):
x = 1
y = 2
def f():
z = x + y
d = sys._getframe().f_locals
self.assertEqual(d['x'], 1)
self.assertEqual(d['y'], 2)
d['x'] = 2
d['y'] = 3
f()
self.assertEqual(x, 2)
self.assertEqual(y, 3)
def test_as_dict(self):
x = 1
y = 2
d = sys._getframe().f_locals
# self, x, y, d
self.assertEqual(len(d), 4)
self.assertIs(d['d'], d)
self.assertEqual(set(d.keys()), set(['x', 'y', 'd', 'self']))
self.assertEqual(len(d.values()), 4)
self.assertIn(1, d.values())
self.assertEqual(len(d.items()), 4)
self.assertIn(('x', 1), d.items())
self.assertEqual(d.__getitem__('x'), 1)
d.__setitem__('x', 2)
self.assertEqual(d['x'], 2)
self.assertEqual(d.get('x'), 2)
self.assertIs(d.get('non_exist', None), None)
self.assertEqual(d.__len__(), 4)
self.assertEqual(set([key for key in d]), set(['x', 'y', 'd', 'self']))
self.assertIn('x', d)
self.assertTrue(d.__contains__('x'))
self.assertEqual(reversed(d), list(reversed(d.keys())))
d.update({'x': 3, 'z': 4})
self.assertEqual(d['x'], 3)
self.assertEqual(d['z'], 4)
with self.assertRaises(TypeError):
d.update([1, 2])
self.assertEqual(d.setdefault('x', 5), 3)
self.assertEqual(d.setdefault('new', 5), 5)
self.assertEqual(d['new'], 5)
with self.assertRaises(KeyError):
d['non_exist']
def test_as_number(self):
x = 1
y = 2
d = sys._getframe().f_locals
self.assertIn('z', d | {'z': 3})
d |= {'z': 3}
self.assertEqual(d['z'], 3)
d |= {'y': 3}
self.assertEqual(d['y'], 3)
with self.assertRaises(TypeError):
d |= 3
with self.assertRaises(TypeError):
_ = d | [3]
def test_non_string_key(self):
d = sys._getframe().f_locals
d[1] = 2
self.assertEqual(d[1], 2)
def test_write_with_hidden(self):
def f():
f_locals = [sys._getframe().f_locals for b in [0]][0]
f_locals['b'] = 2
f_locals['c'] = 3
self.assertEqual(b, 2)
self.assertEqual(c, 3)
b = 0
c = 0
f()
def test_local_objects(self):
o = object()
k = '.'.join(['a', 'b', 'c'])
f_locals = sys._getframe().f_locals
f_locals['o'] = f_locals['k']
self.assertEqual(o, 'a.b.c')
def test_copy(self):
x = 0
d = sys._getframe().f_locals
d_copy = d.copy()
self.assertIsInstance(d_copy, dict)
self.assertEqual(d_copy['x'], 0)
d_copy['x'] = 1
self.assertEqual(x, 0)
def test_update_with_self(self):
def f():
f_locals = sys._getframe().f_locals
f_locals.update(f_locals)
f_locals.update(f_locals)
f_locals.update(f_locals)
f()
def test_repr(self):
x = 1
# Introduce a reference cycle
frame = sys._getframe()
self.assertEqual(repr(frame.f_locals), repr(dict(frame.f_locals)))
def test_delete(self):
x = 1
d = sys._getframe().f_locals
with self.assertRaises(TypeError):
del d['x']
with self.assertRaises(AttributeError):
d.clear()
with self.assertRaises(AttributeError):
d.pop('x')
@support.cpython_only
def test_sizeof(self):
proxy = sys._getframe().f_locals
support.check_sizeof(self, proxy, support.calcobjsize("P"))
def test_unsupport(self):
x = 1
d = sys._getframe().f_locals
with self.assertRaises(TypeError):
copy.copy(d)
with self.assertRaises(TypeError):
copy.deepcopy(d)
class TestFrameCApi(unittest.TestCase):
def test_basic(self):
x = 1
ctypes = import_helper.import_module('ctypes')
PyEval_GetFrameLocals = ctypes.pythonapi.PyEval_GetFrameLocals
PyEval_GetFrameLocals.restype = ctypes.py_object
frame_locals = PyEval_GetFrameLocals()
self.assertTrue(type(frame_locals), dict)
self.assertEqual(frame_locals['x'], 1)
frame_locals['x'] = 2
self.assertEqual(x, 1)
PyEval_GetFrameGlobals = ctypes.pythonapi.PyEval_GetFrameGlobals
PyEval_GetFrameGlobals.restype = ctypes.py_object
frame_globals = PyEval_GetFrameGlobals()
self.assertTrue(type(frame_globals), dict)
self.assertIs(frame_globals, globals())
PyEval_GetFrameBuiltins = ctypes.pythonapi.PyEval_GetFrameBuiltins
PyEval_GetFrameBuiltins.restype = ctypes.py_object
frame_builtins = PyEval_GetFrameBuiltins()
self.assertEqual(frame_builtins, __builtins__)
PyFrame_GetLocals = ctypes.pythonapi.PyFrame_GetLocals
PyFrame_GetLocals.argtypes = [ctypes.py_object]
PyFrame_GetLocals.restype = ctypes.py_object
frame = sys._getframe()
f_locals = PyFrame_GetLocals(frame)
self.assertTrue(f_locals['x'], 1)
f_locals['x'] = 2
self.assertEqual(x, 2)
class TestIncompleteFrameAreInvisible(unittest.TestCase):
def test_issue95818(self):
# See GH-95818 for details
code = textwrap.dedent(f"""
import gc
gc.set_threshold(1,1,1)
class GCHello:
def __del__(self):
print("Destroyed from gc")
def gen():
yield
fd = open({__file__!r})
l = [fd, GCHello()]
l.append(l)
del fd
del l
gen()
""")
assert_python_ok("-c", code)
@support.cpython_only
@threading_helper.requires_working_threading()
def test_sneaky_frame_object_teardown(self):
class SneakyDel:
def __del__(self):
"""
Stash a reference to the entire stack for walking later.
It may look crazy, but you'd be surprised how common this is
when using a test runner (like pytest). The typical recipe is:
ResourceWarning + -Werror + a custom sys.unraisablehook.
"""
nonlocal sneaky_frame_object
sneaky_frame_object = sys._getframe()
class SneakyThread(threading.Thread):
"""
A separate thread isn't needed to make this code crash, but it does
make crashes more consistent, since it means sneaky_frame_object is
backed by freed memory after the thread completes!
"""
def run(self):
"""Run SneakyDel.__del__ as this frame is popped."""
ref = SneakyDel()
sneaky_frame_object = None
t = SneakyThread()
t.start()
t.join()
# sneaky_frame_object can be anything, really, but it's crucial that
# SneakyThread.run's frame isn't anywhere on the stack while it's being
# torn down:
self.assertIsNotNone(sneaky_frame_object)
while sneaky_frame_object is not None:
self.assertIsNot(
sneaky_frame_object.f_code, SneakyThread.run.__code__
)
sneaky_frame_object = sneaky_frame_object.f_back
def test_entry_frames_are_invisible_during_teardown(self):
class C:
"""A weakref'able class."""
def f():
"""Try to find globals and locals as this frame is being cleared."""
ref = C()
# Ignore the fact that exec(C()) is a nonsense callback. We're only
# using exec here because it tries to access the current frame's
# globals and locals. If it's trying to get those from a shim frame,
# we'll crash before raising:
return weakref.ref(ref, exec)
with support.catch_unraisable_exception() as catcher:
# Call from C, so there is a shim frame directly above f:
weak = operator.call(f) # BOOM!
# Cool, we didn't crash. Check that the callback actually happened:
self.assertIs(catcher.unraisable.exc_type, TypeError)
self.assertIsNone(weak())
@unittest.skipIf(_testcapi is None, 'need _testcapi')
class TestCAPI(unittest.TestCase):
def getframe(self):
return sys._getframe()
def test_frame_getters(self):
frame = self.getframe()
self.assertEqual(frame.f_locals, _testcapi.frame_getlocals(frame))
self.assertIs(frame.f_globals, _testcapi.frame_getglobals(frame))
self.assertIs(frame.f_builtins, _testcapi.frame_getbuiltins(frame))
self.assertEqual(frame.f_lasti, _testcapi.frame_getlasti(frame))
def test_getvar(self):
current_frame = sys._getframe()
x = 1
self.assertEqual(_testcapi.frame_getvar(current_frame, "x"), 1)
self.assertEqual(_testcapi.frame_getvarstring(current_frame, b"x"), 1)
with self.assertRaises(NameError):
_testcapi.frame_getvar(current_frame, "y")
with self.assertRaises(NameError):
_testcapi.frame_getvarstring(current_frame, b"y")
# wrong name type
with self.assertRaises(TypeError):
_testcapi.frame_getvar(current_frame, b'x')
with self.assertRaises(TypeError):
_testcapi.frame_getvar(current_frame, 123)
def getgenframe(self):
yield sys._getframe()
def test_frame_get_generator(self):
gen = self.getgenframe()
frame = next(gen)
self.assertIs(gen, _testcapi.frame_getgenerator(frame))
def test_frame_fback_api(self):
"""Test that accessing `f_back` does not cause a segmentation fault on
a frame created with `PyFrame_New` (GH-99110)."""
def dummy():
pass
frame = _testcapi.frame_new(dummy.__code__, globals(), locals())
# The following line should not cause a segmentation fault.
self.assertIsNone(frame.f_back)
if __name__ == "__main__":
unittest.main()
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