"""Unit tests for contextlib.py, and other context managers."""
import sys
import tempfile
import unittest
from contextlib import * # Tests __all__
from test import test_support
try:
import threading
except ImportError:
threading = None
class ContextManagerTestCase(unittest.TestCase):
def test_contextmanager_plain(self):
state = []
@contextmanager
def woohoo():
state.append(1)
yield 42
state.append(999)
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_finally(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
finally:
state.append(999)
with self.assertRaises(ZeroDivisionError):
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError()
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_no_reraise(self):
@contextmanager
def whee():
yield
ctx = whee()
ctx.__enter__()
# Calling __exit__ should not result in an exception
self.assertFalse(ctx.__exit__(TypeError, TypeError("foo"), None))
def test_contextmanager_trap_yield_after_throw(self):
@contextmanager
def whoo():
try:
yield
except:
yield
ctx = whoo()
ctx.__enter__()
self.assertRaises(
RuntimeError, ctx.__exit__, TypeError, TypeError("foo"), None
)
def test_contextmanager_except(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
except ZeroDivisionError, e:
state.append(e.args[0])
self.assertEqual(state, [1, 42, 999])
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError(999)
self.assertEqual(state, [1, 42, 999])
def _create_contextmanager_attribs(self):
def attribs(**kw):
def decorate(func):
for k,v in kw.items():
setattr(func,k,v)
return func
return decorate
@contextmanager
@attribs(foo='bar')
def baz(spam):
"""Whee!"""
return baz
def test_contextmanager_attribs(self):
baz = self._create_contextmanager_attribs()
self.assertEqual(baz.__name__,'baz')
self.assertEqual(baz.foo, 'bar')
@unittest.skipIf(sys.flags.optimize >= 2,
"Docstrings are omitted with -O2 and above")
def test_contextmanager_doc_attrib(self):
baz = self._create_contextmanager_attribs()
self.assertEqual(baz.__doc__, "Whee!")
class NestedTestCase(unittest.TestCase):
# XXX This needs more work
def test_nested(self):
@contextmanager
def a():
yield 1
@contextmanager
def b():
yield 2
@contextmanager
def c():
yield 3
with nested(a(), b(), c()) as (x, y, z):
self.assertEqual(x, 1)
self.assertEqual(y, 2)
self.assertEqual(z, 3)
def test_nested_cleanup(self):
state = []
@contextmanager
def a():
state.append(1)
try:
yield 2
finally:
state.append(3)
@contextmanager
def b():
state.append(4)
try:
yield 5
finally:
state.append(6)
with self.assertRaises(ZeroDivisionError):
with nested(a(), b()) as (x, y):
state.append(x)
state.append(y)
1 // 0
self.assertEqual(state, [1, 4, 2, 5, 6, 3])
def test_nested_right_exception(self):
@contextmanager
def a():
yield 1
class b(object):
def __enter__(self):
return 2
def __exit__(self, *exc_info):
try:
raise Exception()
except:
pass
with self.assertRaises(ZeroDivisionError):
with nested(a(), b()) as (x, y):
1 // 0
self.assertEqual((x, y), (1, 2))
def test_nested_b_swallows(self):
@contextmanager
def a():
yield
@contextmanager
def b():
try:
yield
except:
# Swallow the exception
pass
try:
with nested(a(), b()):
1 // 0
except ZeroDivisionError:
self.fail("Didn't swallow ZeroDivisionError")
def test_nested_break(self):
@contextmanager
def a():
yield
state = 0
while True:
state += 1
with nested(a(), a()):
break
state += 10
self.assertEqual(state, 1)
def test_nested_continue(self):
@contextmanager
def a():
yield
state = 0
while state < 3:
state += 1
with nested(a(), a()):
continue
state += 10
self.assertEqual(state, 3)
def test_nested_return(self):
@contextmanager
def a():
try:
yield
except:
pass
def foo():
with nested(a(), a()):
return 1
return 10
self.assertEqual(foo(), 1)
class ClosingTestCase(unittest.TestCase):
# XXX This needs more work
def test_closing(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
with closing(x) as y:
self.assertEqual(x, y)
self.assertEqual(state, [1])
def test_closing_error(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
with self.assertRaises(ZeroDivisionError):
with closing(x) as y:
self.assertEqual(x, y)
1 // 0
self.assertEqual(state, [1])
class FileContextTestCase(unittest.TestCase):
def testWithOpen(self):
tfn = tempfile.mktemp()
try:
f = None
with open(tfn, "w") as f:
self.assertFalse(f.closed)
f.write("Booh\n")
self.assertTrue(f.closed)
f = None
with self.assertRaises(ZeroDivisionError):
with open(tfn, "r") as f:
self.assertFalse(f.closed)
self.assertEqual(f.read(), "Booh\n")
1 // 0
self.assertTrue(f.closed)
finally:
test_support.unlink(tfn)
@unittest.skipUnless(threading, 'Threading required for this test.')
class LockContextTestCase(unittest.TestCase):
def boilerPlate(self, lock, locked):
self.assertFalse(locked())
with lock:
self.assertTrue(locked())
self.assertFalse(locked())
with self.assertRaises(ZeroDivisionError):
with lock:
self.assertTrue(locked())
1 // 0
self.assertFalse(locked())
def testWithLock(self):
lock = threading.Lock()
self.boilerPlate(lock, lock.locked)
def testWithRLock(self):
lock = threading.RLock()
self.boilerPlate(lock, lock._is_owned)
def testWithCondition(self):
lock = threading.Condition()
def locked():
return lock._is_owned()
self.boilerPlate(lock, locked)
def testWithSemaphore(self):
lock = threading.Semaphore()
def locked():
if lock.acquire(False):
lock.release()
return False
else:
return True
self.boilerPlate(lock, locked)
def testWithBoundedSemaphore(self):
lock = threading.BoundedSemaphore()
def locked():
if lock.acquire(False):
lock.release()
return False
else:
return True
self.boilerPlate(lock, locked)
# This is needed to make the test actually run under regrtest.py!
def test_main():
with test_support.check_warnings(("With-statements now directly support "
"multiple context managers",
DeprecationWarning)):
test_support.run_unittest(__name__)
if __name__ == "__main__":
test_main()