mirror of
https://github.com/python/cpython.git
synced 2025-10-26 03:04:41 +00:00
059def58a5
- added test cases to ensure docstrings are reasonable - also updates various comments in contextlib for accuracy - identifed #19404 as an issue making it difficult to provide good help output on generator based context manager instances
761 lines
23 KiB
Python
761 lines
23 KiB
Python
"""Unit tests for contextlib.py, and other context managers."""
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import io
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import sys
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import tempfile
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import unittest
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from contextlib import * # Tests __all__
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from test import support
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try:
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import threading
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except ImportError:
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threading = None
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class ContextManagerTestCase(unittest.TestCase):
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def test_instance_docstring_given_function_docstring(self):
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# Issue 19330: ensure context manager instances have good docstrings
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# See http://bugs.python.org/issue19404 for why this doesn't currently
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# affect help() output :(
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def gen_with_docstring():
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"""This has a docstring"""
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yield
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gen_docstring = gen_with_docstring.__doc__
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cm_with_docstring = contextmanager(gen_with_docstring)
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self.assertEqual(cm_with_docstring.__doc__, gen_docstring)
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obj = cm_with_docstring()
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self.assertEqual(obj.__doc__, gen_docstring)
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self.assertNotEqual(obj.__doc__, type(obj).__doc__)
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def test_contextmanager_plain(self):
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state = []
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@contextmanager
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def woohoo():
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state.append(1)
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yield 42
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state.append(999)
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with woohoo() as x:
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self.assertEqual(state, [1])
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self.assertEqual(x, 42)
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state.append(x)
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self.assertEqual(state, [1, 42, 999])
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def test_contextmanager_finally(self):
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state = []
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@contextmanager
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def woohoo():
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state.append(1)
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try:
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yield 42
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finally:
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state.append(999)
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with self.assertRaises(ZeroDivisionError):
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with woohoo() as x:
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self.assertEqual(state, [1])
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self.assertEqual(x, 42)
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state.append(x)
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raise ZeroDivisionError()
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self.assertEqual(state, [1, 42, 999])
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def test_contextmanager_no_reraise(self):
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@contextmanager
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def whee():
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yield
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ctx = whee()
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ctx.__enter__()
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# Calling __exit__ should not result in an exception
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self.assertFalse(ctx.__exit__(TypeError, TypeError("foo"), None))
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def test_contextmanager_trap_yield_after_throw(self):
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@contextmanager
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def whoo():
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try:
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yield
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except:
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yield
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ctx = whoo()
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ctx.__enter__()
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self.assertRaises(
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RuntimeError, ctx.__exit__, TypeError, TypeError("foo"), None
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)
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def test_contextmanager_except(self):
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state = []
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@contextmanager
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def woohoo():
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state.append(1)
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try:
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yield 42
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except ZeroDivisionError as e:
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state.append(e.args[0])
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self.assertEqual(state, [1, 42, 999])
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with woohoo() as x:
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self.assertEqual(state, [1])
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self.assertEqual(x, 42)
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state.append(x)
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raise ZeroDivisionError(999)
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self.assertEqual(state, [1, 42, 999])
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def _create_contextmanager_attribs(self):
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def attribs(**kw):
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def decorate(func):
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for k,v in kw.items():
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setattr(func,k,v)
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return func
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return decorate
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@contextmanager
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@attribs(foo='bar')
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def baz(spam):
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"""Whee!"""
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return baz
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def test_contextmanager_attribs(self):
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baz = self._create_contextmanager_attribs()
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self.assertEqual(baz.__name__,'baz')
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self.assertEqual(baz.foo, 'bar')
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@unittest.skipIf(sys.flags.optimize >= 2,
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"Docstrings are omitted with -O2 and above")
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def test_contextmanager_doc_attrib(self):
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baz = self._create_contextmanager_attribs()
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self.assertEqual(baz.__doc__, "Whee!")
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class ClosingTestCase(unittest.TestCase):
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def test_instance_docs(self):
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# Issue 19330: ensure context manager instances have good docstrings
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cm_docstring = closing.__doc__
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obj = closing(None)
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self.assertEqual(obj.__doc__, cm_docstring)
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def test_closing(self):
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state = []
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class C:
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def close(self):
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state.append(1)
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x = C()
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self.assertEqual(state, [])
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with closing(x) as y:
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self.assertEqual(x, y)
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self.assertEqual(state, [1])
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def test_closing_error(self):
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state = []
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class C:
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def close(self):
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state.append(1)
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x = C()
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self.assertEqual(state, [])
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with self.assertRaises(ZeroDivisionError):
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with closing(x) as y:
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self.assertEqual(x, y)
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1 / 0
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self.assertEqual(state, [1])
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class FileContextTestCase(unittest.TestCase):
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def testWithOpen(self):
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tfn = tempfile.mktemp()
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try:
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f = None
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with open(tfn, "w") as f:
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self.assertFalse(f.closed)
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f.write("Booh\n")
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self.assertTrue(f.closed)
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f = None
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with self.assertRaises(ZeroDivisionError):
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with open(tfn, "r") as f:
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self.assertFalse(f.closed)
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self.assertEqual(f.read(), "Booh\n")
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1 / 0
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self.assertTrue(f.closed)
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finally:
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support.unlink(tfn)
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@unittest.skipUnless(threading, 'Threading required for this test.')
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class LockContextTestCase(unittest.TestCase):
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def boilerPlate(self, lock, locked):
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self.assertFalse(locked())
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with lock:
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self.assertTrue(locked())
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self.assertFalse(locked())
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with self.assertRaises(ZeroDivisionError):
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with lock:
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self.assertTrue(locked())
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1 / 0
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self.assertFalse(locked())
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def testWithLock(self):
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lock = threading.Lock()
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self.boilerPlate(lock, lock.locked)
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def testWithRLock(self):
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lock = threading.RLock()
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self.boilerPlate(lock, lock._is_owned)
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def testWithCondition(self):
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lock = threading.Condition()
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def locked():
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return lock._is_owned()
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self.boilerPlate(lock, locked)
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def testWithSemaphore(self):
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lock = threading.Semaphore()
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def locked():
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if lock.acquire(False):
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lock.release()
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return False
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else:
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return True
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self.boilerPlate(lock, locked)
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def testWithBoundedSemaphore(self):
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lock = threading.BoundedSemaphore()
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def locked():
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if lock.acquire(False):
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lock.release()
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return False
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else:
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return True
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self.boilerPlate(lock, locked)
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class mycontext(ContextDecorator):
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"""Example decoration-compatible context manager for testing"""
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started = False
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exc = None
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catch = False
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def __enter__(self):
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self.started = True
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return self
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def __exit__(self, *exc):
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self.exc = exc
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return self.catch
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class TestContextDecorator(unittest.TestCase):
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def test_instance_docs(self):
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# Issue 19330: ensure context manager instances have good docstrings
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cm_docstring = mycontext.__doc__
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obj = mycontext()
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self.assertEqual(obj.__doc__, cm_docstring)
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def test_contextdecorator(self):
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context = mycontext()
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with context as result:
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self.assertIs(result, context)
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self.assertTrue(context.started)
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self.assertEqual(context.exc, (None, None, None))
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def test_contextdecorator_with_exception(self):
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context = mycontext()
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with self.assertRaisesRegex(NameError, 'foo'):
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with context:
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raise NameError('foo')
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self.assertIsNotNone(context.exc)
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self.assertIs(context.exc[0], NameError)
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context = mycontext()
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context.catch = True
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with context:
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raise NameError('foo')
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self.assertIsNotNone(context.exc)
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self.assertIs(context.exc[0], NameError)
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def test_decorator(self):
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context = mycontext()
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@context
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def test():
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self.assertIsNone(context.exc)
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self.assertTrue(context.started)
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test()
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self.assertEqual(context.exc, (None, None, None))
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def test_decorator_with_exception(self):
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context = mycontext()
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@context
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def test():
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self.assertIsNone(context.exc)
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self.assertTrue(context.started)
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raise NameError('foo')
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with self.assertRaisesRegex(NameError, 'foo'):
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test()
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self.assertIsNotNone(context.exc)
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self.assertIs(context.exc[0], NameError)
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def test_decorating_method(self):
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context = mycontext()
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class Test(object):
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@context
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def method(self, a, b, c=None):
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self.a = a
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self.b = b
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self.c = c
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# these tests are for argument passing when used as a decorator
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test = Test()
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test.method(1, 2)
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self.assertEqual(test.a, 1)
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self.assertEqual(test.b, 2)
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self.assertEqual(test.c, None)
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test = Test()
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test.method('a', 'b', 'c')
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self.assertEqual(test.a, 'a')
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self.assertEqual(test.b, 'b')
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self.assertEqual(test.c, 'c')
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test = Test()
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test.method(a=1, b=2)
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self.assertEqual(test.a, 1)
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self.assertEqual(test.b, 2)
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def test_typo_enter(self):
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class mycontext(ContextDecorator):
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def __unter__(self):
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pass
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def __exit__(self, *exc):
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pass
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with self.assertRaises(AttributeError):
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with mycontext():
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pass
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def test_typo_exit(self):
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class mycontext(ContextDecorator):
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def __enter__(self):
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pass
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def __uxit__(self, *exc):
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pass
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with self.assertRaises(AttributeError):
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with mycontext():
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pass
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def test_contextdecorator_as_mixin(self):
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class somecontext(object):
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started = False
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exc = None
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def __enter__(self):
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self.started = True
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return self
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def __exit__(self, *exc):
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self.exc = exc
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class mycontext(somecontext, ContextDecorator):
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pass
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context = mycontext()
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@context
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def test():
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self.assertIsNone(context.exc)
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self.assertTrue(context.started)
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test()
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self.assertEqual(context.exc, (None, None, None))
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def test_contextmanager_as_decorator(self):
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@contextmanager
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def woohoo(y):
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state.append(y)
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yield
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state.append(999)
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state = []
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@woohoo(1)
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def test(x):
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self.assertEqual(state, [1])
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state.append(x)
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test('something')
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self.assertEqual(state, [1, 'something', 999])
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# Issue #11647: Ensure the decorated function is 'reusable'
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state = []
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test('something else')
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self.assertEqual(state, [1, 'something else', 999])
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class TestExitStack(unittest.TestCase):
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def test_instance_docs(self):
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# Issue 19330: ensure context manager instances have good docstrings
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cm_docstring = ExitStack.__doc__
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obj = ExitStack()
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self.assertEqual(obj.__doc__, cm_docstring)
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def test_no_resources(self):
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with ExitStack():
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pass
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def test_callback(self):
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expected = [
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((), {}),
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((1,), {}),
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((1,2), {}),
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((), dict(example=1)),
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((1,), dict(example=1)),
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((1,2), dict(example=1)),
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]
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result = []
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def _exit(*args, **kwds):
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"""Test metadata propagation"""
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result.append((args, kwds))
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with ExitStack() as stack:
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for args, kwds in reversed(expected):
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if args and kwds:
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f = stack.callback(_exit, *args, **kwds)
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elif args:
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f = stack.callback(_exit, *args)
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elif kwds:
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f = stack.callback(_exit, **kwds)
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else:
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f = stack.callback(_exit)
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self.assertIs(f, _exit)
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for wrapper in stack._exit_callbacks:
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self.assertIs(wrapper.__wrapped__, _exit)
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self.assertNotEqual(wrapper.__name__, _exit.__name__)
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self.assertIsNone(wrapper.__doc__, _exit.__doc__)
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self.assertEqual(result, expected)
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def test_push(self):
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exc_raised = ZeroDivisionError
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def _expect_exc(exc_type, exc, exc_tb):
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self.assertIs(exc_type, exc_raised)
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def _suppress_exc(*exc_details):
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return True
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def _expect_ok(exc_type, exc, exc_tb):
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self.assertIsNone(exc_type)
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self.assertIsNone(exc)
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self.assertIsNone(exc_tb)
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class ExitCM(object):
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def __init__(self, check_exc):
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self.check_exc = check_exc
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def __enter__(self):
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self.fail("Should not be called!")
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def __exit__(self, *exc_details):
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self.check_exc(*exc_details)
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with ExitStack() as stack:
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stack.push(_expect_ok)
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self.assertIs(stack._exit_callbacks[-1], _expect_ok)
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cm = ExitCM(_expect_ok)
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stack.push(cm)
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self.assertIs(stack._exit_callbacks[-1].__self__, cm)
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stack.push(_suppress_exc)
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self.assertIs(stack._exit_callbacks[-1], _suppress_exc)
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cm = ExitCM(_expect_exc)
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stack.push(cm)
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self.assertIs(stack._exit_callbacks[-1].__self__, cm)
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stack.push(_expect_exc)
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self.assertIs(stack._exit_callbacks[-1], _expect_exc)
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stack.push(_expect_exc)
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self.assertIs(stack._exit_callbacks[-1], _expect_exc)
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1/0
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def test_enter_context(self):
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class TestCM(object):
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def __enter__(self):
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result.append(1)
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def __exit__(self, *exc_details):
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result.append(3)
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result = []
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cm = TestCM()
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with ExitStack() as stack:
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@stack.callback # Registered first => cleaned up last
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def _exit():
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result.append(4)
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self.assertIsNotNone(_exit)
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stack.enter_context(cm)
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self.assertIs(stack._exit_callbacks[-1].__self__, cm)
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result.append(2)
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self.assertEqual(result, [1, 2, 3, 4])
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def test_close(self):
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result = []
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with ExitStack() as stack:
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@stack.callback
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def _exit():
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result.append(1)
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self.assertIsNotNone(_exit)
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stack.close()
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result.append(2)
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self.assertEqual(result, [1, 2])
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def test_pop_all(self):
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result = []
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with ExitStack() as stack:
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@stack.callback
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def _exit():
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result.append(3)
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self.assertIsNotNone(_exit)
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new_stack = stack.pop_all()
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result.append(1)
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result.append(2)
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new_stack.close()
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self.assertEqual(result, [1, 2, 3])
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def test_exit_raise(self):
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with self.assertRaises(ZeroDivisionError):
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with ExitStack() as stack:
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stack.push(lambda *exc: False)
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1/0
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def test_exit_suppress(self):
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with ExitStack() as stack:
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stack.push(lambda *exc: True)
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1/0
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def test_exit_exception_chaining_reference(self):
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# Sanity check to make sure that ExitStack chaining matches
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# actual nested with statements
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class RaiseExc:
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def __init__(self, exc):
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self.exc = exc
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def __enter__(self):
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return self
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def __exit__(self, *exc_details):
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raise self.exc
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class RaiseExcWithContext:
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def __init__(self, outer, inner):
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self.outer = outer
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self.inner = inner
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def __enter__(self):
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return self
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def __exit__(self, *exc_details):
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try:
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raise self.inner
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except:
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raise self.outer
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class SuppressExc:
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def __enter__(self):
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return self
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def __exit__(self, *exc_details):
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type(self).saved_details = exc_details
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return True
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try:
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with RaiseExc(IndexError):
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with RaiseExcWithContext(KeyError, AttributeError):
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with SuppressExc():
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with RaiseExc(ValueError):
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1 / 0
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except IndexError as exc:
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self.assertIsInstance(exc.__context__, KeyError)
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self.assertIsInstance(exc.__context__.__context__, AttributeError)
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# Inner exceptions were suppressed
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self.assertIsNone(exc.__context__.__context__.__context__)
|
|
else:
|
|
self.fail("Expected IndexError, but no exception was raised")
|
|
# Check the inner exceptions
|
|
inner_exc = SuppressExc.saved_details[1]
|
|
self.assertIsInstance(inner_exc, ValueError)
|
|
self.assertIsInstance(inner_exc.__context__, ZeroDivisionError)
|
|
|
|
def test_exit_exception_chaining(self):
|
|
# Ensure exception chaining matches the reference behaviour
|
|
def raise_exc(exc):
|
|
raise exc
|
|
|
|
saved_details = None
|
|
def suppress_exc(*exc_details):
|
|
nonlocal saved_details
|
|
saved_details = exc_details
|
|
return True
|
|
|
|
try:
|
|
with ExitStack() as stack:
|
|
stack.callback(raise_exc, IndexError)
|
|
stack.callback(raise_exc, KeyError)
|
|
stack.callback(raise_exc, AttributeError)
|
|
stack.push(suppress_exc)
|
|
stack.callback(raise_exc, ValueError)
|
|
1 / 0
|
|
except IndexError as exc:
|
|
self.assertIsInstance(exc.__context__, KeyError)
|
|
self.assertIsInstance(exc.__context__.__context__, AttributeError)
|
|
# Inner exceptions were suppressed
|
|
self.assertIsNone(exc.__context__.__context__.__context__)
|
|
else:
|
|
self.fail("Expected IndexError, but no exception was raised")
|
|
# Check the inner exceptions
|
|
inner_exc = saved_details[1]
|
|
self.assertIsInstance(inner_exc, ValueError)
|
|
self.assertIsInstance(inner_exc.__context__, ZeroDivisionError)
|
|
|
|
def test_exit_exception_non_suppressing(self):
|
|
# http://bugs.python.org/issue19092
|
|
def raise_exc(exc):
|
|
raise exc
|
|
|
|
def suppress_exc(*exc_details):
|
|
return True
|
|
|
|
try:
|
|
with ExitStack() as stack:
|
|
stack.callback(lambda: None)
|
|
stack.callback(raise_exc, IndexError)
|
|
except Exception as exc:
|
|
self.assertIsInstance(exc, IndexError)
|
|
else:
|
|
self.fail("Expected IndexError, but no exception was raised")
|
|
|
|
try:
|
|
with ExitStack() as stack:
|
|
stack.callback(raise_exc, KeyError)
|
|
stack.push(suppress_exc)
|
|
stack.callback(raise_exc, IndexError)
|
|
except Exception as exc:
|
|
self.assertIsInstance(exc, KeyError)
|
|
else:
|
|
self.fail("Expected KeyError, but no exception was raised")
|
|
|
|
def test_body_exception_suppress(self):
|
|
def suppress_exc(*exc_details):
|
|
return True
|
|
try:
|
|
with ExitStack() as stack:
|
|
stack.push(suppress_exc)
|
|
1/0
|
|
except IndexError as exc:
|
|
self.fail("Expected no exception, got IndexError")
|
|
|
|
def test_exit_exception_chaining_suppress(self):
|
|
with ExitStack() as stack:
|
|
stack.push(lambda *exc: True)
|
|
stack.push(lambda *exc: 1/0)
|
|
stack.push(lambda *exc: {}[1])
|
|
|
|
def test_excessive_nesting(self):
|
|
# The original implementation would die with RecursionError here
|
|
with ExitStack() as stack:
|
|
for i in range(10000):
|
|
stack.callback(int)
|
|
|
|
def test_instance_bypass(self):
|
|
class Example(object): pass
|
|
cm = Example()
|
|
cm.__exit__ = object()
|
|
stack = ExitStack()
|
|
self.assertRaises(AttributeError, stack.enter_context, cm)
|
|
stack.push(cm)
|
|
self.assertIs(stack._exit_callbacks[-1], cm)
|
|
|
|
class TestRedirectStdout(unittest.TestCase):
|
|
|
|
def test_instance_docs(self):
|
|
# Issue 19330: ensure context manager instances have good docstrings
|
|
cm_docstring = redirect_stdout.__doc__
|
|
obj = redirect_stdout(None)
|
|
self.assertEqual(obj.__doc__, cm_docstring)
|
|
|
|
def test_redirect_to_string_io(self):
|
|
f = io.StringIO()
|
|
msg = "Consider an API like help(), which prints directly to stdout"
|
|
with redirect_stdout(f):
|
|
print(msg)
|
|
s = f.getvalue().strip()
|
|
self.assertEqual(s, msg)
|
|
|
|
def test_enter_result_is_target(self):
|
|
f = io.StringIO()
|
|
with redirect_stdout(f) as enter_result:
|
|
self.assertIs(enter_result, f)
|
|
|
|
def test_cm_is_reusable(self):
|
|
f = io.StringIO()
|
|
write_to_f = redirect_stdout(f)
|
|
with write_to_f:
|
|
print("Hello", end=" ")
|
|
with write_to_f:
|
|
print("World!")
|
|
s = f.getvalue()
|
|
self.assertEqual(s, "Hello World!\n")
|
|
|
|
# If this is ever made reentrant, update the reusable-but-not-reentrant
|
|
# example at the end of the contextlib docs accordingly.
|
|
def test_nested_reentry_fails(self):
|
|
f = io.StringIO()
|
|
write_to_f = redirect_stdout(f)
|
|
with self.assertRaisesRegex(RuntimeError, "Cannot reenter"):
|
|
with write_to_f:
|
|
print("Hello", end=" ")
|
|
with write_to_f:
|
|
print("World!")
|
|
|
|
|
|
class TestSuppress(unittest.TestCase):
|
|
|
|
def test_instance_docs(self):
|
|
# Issue 19330: ensure context manager instances have good docstrings
|
|
cm_docstring = suppress.__doc__
|
|
obj = suppress()
|
|
self.assertEqual(obj.__doc__, cm_docstring)
|
|
|
|
def test_no_result_from_enter(self):
|
|
with suppress(ValueError) as enter_result:
|
|
self.assertIsNone(enter_result)
|
|
|
|
def test_no_exception(self):
|
|
with suppress(ValueError):
|
|
self.assertEqual(pow(2, 5), 32)
|
|
|
|
def test_exact_exception(self):
|
|
with suppress(TypeError):
|
|
len(5)
|
|
|
|
def test_exception_hierarchy(self):
|
|
with suppress(LookupError):
|
|
'Hello'[50]
|
|
|
|
def test_other_exception(self):
|
|
with self.assertRaises(ZeroDivisionError):
|
|
with suppress(TypeError):
|
|
1/0
|
|
|
|
def test_no_args(self):
|
|
with self.assertRaises(ZeroDivisionError):
|
|
with suppress():
|
|
1/0
|
|
|
|
def test_multiple_exception_args(self):
|
|
with suppress(ZeroDivisionError, TypeError):
|
|
1/0
|
|
with suppress(ZeroDivisionError, TypeError):
|
|
len(5)
|
|
|
|
def test_cm_is_reentrant(self):
|
|
ignore_exceptions = suppress(Exception)
|
|
with ignore_exceptions:
|
|
pass
|
|
with ignore_exceptions:
|
|
len(5)
|
|
with ignore_exceptions:
|
|
1/0
|
|
with ignore_exceptions: # Check nested usage
|
|
len(5)
|
|
|
|
if __name__ == "__main__":
|
|
unittest.main()
|