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# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Python 2.5+ test cases for failures thrown into generators.
"""
from __future__ import division
import sys
import traceback
from twisted.trial.unittest import TestCase
from twisted.python.failure import Failure
from twisted.internet import defer
# Re-implement getDivisionFailure here instead of using the one in
# test_failure.py in order to avoid creating a cyclic dependency.
def getDivisionFailure():
try:
1/0
except:
f = Failure()
return f
class TwoPointFiveFailureTests(TestCase):
def test_inlineCallbacksTracebacks(self):
"""
inlineCallbacks that re-raise tracebacks into their deferred
should not lose their tracebacsk.
"""
f = getDivisionFailure()
d = defer.Deferred()
try:
f.raiseException()
except:
d.errback()
failures = []
def collect_error(result):
failures.append(result)
def ic(d):
yield d
ic = defer.inlineCallbacks(ic)
ic(d).addErrback(collect_error)
newFailure, = failures
self.assertEqual(
traceback.extract_tb(newFailure.getTracebackObject())[-1][-1],
"1/0"
)
def _throwIntoGenerator(self, f, g):
try:
f.throwExceptionIntoGenerator(g)
except StopIteration:
pass
else:
self.fail("throwExceptionIntoGenerator should have raised "
"StopIteration")
def test_throwExceptionIntoGenerator(self):
"""
It should be possible to throw the exception that a Failure
represents into a generator.
"""
stuff = []
def generator():
try:
yield
except:
stuff.append(sys.exc_info())
else:
self.fail("Yield should have yielded exception.")
g = generator()
f = getDivisionFailure()
g.next()
self._throwIntoGenerator(f, g)
self.assertEqual(stuff[0][0], ZeroDivisionError)
self.assertTrue(isinstance(stuff[0][1], ZeroDivisionError))
self.assertEqual(traceback.extract_tb(stuff[0][2])[-1][-1], "1/0")
def test_findFailureInGenerator(self):
"""
Within an exception handler, it should be possible to find the
original Failure that caused the current exception (if it was
caused by throwExceptionIntoGenerator).
"""
f = getDivisionFailure()
f.cleanFailure()
foundFailures = []
def generator():
try:
yield
except:
foundFailures.append(Failure._findFailure())
else:
self.fail("No exception sent to generator")
g = generator()
g.next()
self._throwIntoGenerator(f, g)
self.assertEqual(foundFailures, [f])
def test_failureConstructionFindsOriginalFailure(self):
"""
When a Failure is constructed in the context of an exception
handler that is handling an exception raised by
throwExceptionIntoGenerator, the new Failure should be chained to that
original Failure.
"""
f = getDivisionFailure()
f.cleanFailure()
newFailures = []
def generator():
try:
yield
except:
newFailures.append(Failure())
else:
self.fail("No exception sent to generator")
g = generator()
g.next()
self._throwIntoGenerator(f, g)
self.assertEqual(len(newFailures), 1)
self.assertEqual(newFailures[0].getTraceback(), f.getTraceback())
def test_ambiguousFailureInGenerator(self):
"""
When a generator reraises a different exception,
L{Failure._findFailure} inside the generator should find the reraised
exception rather than original one.
"""
def generator():
try:
try:
yield
except:
[][1]
except:
self.assertIsInstance(Failure().value, IndexError)
g = generator()
g.next()
f = getDivisionFailure()
self._throwIntoGenerator(f, g)
def test_ambiguousFailureFromGenerator(self):
"""
When a generator reraises a different exception,
L{Failure._findFailure} above the generator should find the reraised
exception rather than original one.
"""
def generator():
try:
yield
except:
[][1]
g = generator()
g.next()
f = getDivisionFailure()
try:
self._throwIntoGenerator(f, g)
except:
self.assertIsInstance(Failure().value, IndexError)
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