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113 lines
2.8 KiB
Python
113 lines
2.8 KiB
Python
import gc
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import sys
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import unittest
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import weakref
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from test import support
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class ClearTest(unittest.TestCase):
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"""
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Tests for frame.clear().
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"""
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def inner(self, x=5, **kwargs):
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1/0
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def outer(self, **kwargs):
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try:
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self.inner(**kwargs)
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except ZeroDivisionError as e:
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exc = e
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return exc
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def clear_traceback_frames(self, tb):
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"""
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Clear all frames in a traceback.
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"""
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while tb is not None:
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tb.tb_frame.clear()
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tb = tb.tb_next
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def test_clear_locals(self):
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class C:
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pass
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c = C()
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wr = weakref.ref(c)
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exc = self.outer(c=c)
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del c
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support.gc_collect()
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# A reference to c is held through the frames
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self.assertIsNot(None, wr())
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self.clear_traceback_frames(exc.__traceback__)
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support.gc_collect()
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# The reference was released by .clear()
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self.assertIs(None, wr())
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def test_clear_generator(self):
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endly = False
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def g():
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nonlocal endly
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try:
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yield
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inner()
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finally:
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endly = True
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gen = g()
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next(gen)
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self.assertFalse(endly)
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# Clearing the frame closes the generator
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gen.gi_frame.clear()
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self.assertTrue(endly)
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def test_clear_executing(self):
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# Attempting to clear an executing frame is forbidden.
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try:
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1/0
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except ZeroDivisionError as e:
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f = e.__traceback__.tb_frame
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with self.assertRaises(RuntimeError):
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f.clear()
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with self.assertRaises(RuntimeError):
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f.f_back.clear()
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def test_clear_executing_generator(self):
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# Attempting to clear an executing generator frame is forbidden.
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endly = False
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def g():
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nonlocal endly
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try:
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1/0
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except ZeroDivisionError as e:
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f = e.__traceback__.tb_frame
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with self.assertRaises(RuntimeError):
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f.clear()
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with self.assertRaises(RuntimeError):
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f.f_back.clear()
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yield f
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finally:
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endly = True
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gen = g()
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f = next(gen)
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self.assertFalse(endly)
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@support.cpython_only
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def test_clear_refcycles(self):
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# .clear() doesn't leave any refcycle behin
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with support.disable_gc():
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class C:
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pass
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c = C()
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wr = weakref.ref(c)
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exc = self.outer(c=c)
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del c
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self.assertIsNot(None, wr())
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self.clear_traceback_frames(exc.__traceback__)
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self.assertIs(None, wr())
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def test_main():
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support.run_unittest(__name__)
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if __name__ == "__main__":
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test_main()
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