240 lines
8.8 KiB
Python
240 lines
8.8 KiB
Python
import unittest
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import __builtin__
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import exceptions
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import warnings
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from test.test_support import run_unittest, check_warnings
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import os
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import sys
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from platform import system as platform_system
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DEPRECATION_WARNINGS = ["BaseException.message has been deprecated"]
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if sys.py3kwarning:
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DEPRECATION_WARNINGS.extend(
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["exceptions must derive from BaseException",
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"catching classes that don't inherit from BaseException is not allowed",
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"__get(item|slice)__ not supported for exception classes"])
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_deprecations = [(msg, DeprecationWarning) for msg in DEPRECATION_WARNINGS]
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# Silence Py3k and other deprecation warnings
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def ignore_deprecation_warnings(func):
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"""Ignore the known DeprecationWarnings."""
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def wrapper(*args, **kw):
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with check_warnings(*_deprecations, quiet=True):
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return func(*args, **kw)
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return wrapper
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class ExceptionClassTests(unittest.TestCase):
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"""Tests for anything relating to exception objects themselves (e.g.,
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inheritance hierarchy)"""
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def test_builtins_new_style(self):
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self.assertTrue(issubclass(Exception, object))
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@ignore_deprecation_warnings
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def verify_instance_interface(self, ins):
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for attr in ("args", "message", "__str__", "__repr__", "__getitem__"):
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self.assertTrue(hasattr(ins, attr),
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"%s missing %s attribute" %
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(ins.__class__.__name__, attr))
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def test_inheritance(self):
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# Make sure the inheritance hierarchy matches the documentation
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exc_set = set(x for x in dir(exceptions) if not x.startswith('_'))
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inheritance_tree = open(os.path.join(os.path.split(__file__)[0],
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'exception_hierarchy.txt'))
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try:
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superclass_name = inheritance_tree.readline().rstrip()
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try:
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last_exc = getattr(__builtin__, superclass_name)
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except AttributeError:
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self.fail("base class %s not a built-in" % superclass_name)
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self.assertIn(superclass_name, exc_set)
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exc_set.discard(superclass_name)
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superclasses = [] # Loop will insert base exception
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last_depth = 0
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for exc_line in inheritance_tree:
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exc_line = exc_line.rstrip()
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depth = exc_line.rindex('-')
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exc_name = exc_line[depth+2:] # Slice past space
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if '(' in exc_name:
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paren_index = exc_name.index('(')
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platform_name = exc_name[paren_index+1:-1]
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exc_name = exc_name[:paren_index-1] # Slice off space
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if platform_system() != platform_name:
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exc_set.discard(exc_name)
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continue
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if '[' in exc_name:
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left_bracket = exc_name.index('[')
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exc_name = exc_name[:left_bracket-1] # cover space
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try:
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exc = getattr(__builtin__, exc_name)
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except AttributeError:
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self.fail("%s not a built-in exception" % exc_name)
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if last_depth < depth:
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superclasses.append((last_depth, last_exc))
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elif last_depth > depth:
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while superclasses[-1][0] >= depth:
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superclasses.pop()
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self.assertTrue(issubclass(exc, superclasses[-1][1]),
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"%s is not a subclass of %s" % (exc.__name__,
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superclasses[-1][1].__name__))
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try: # Some exceptions require arguments; just skip them
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self.verify_instance_interface(exc())
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except TypeError:
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pass
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self.assertIn(exc_name, exc_set)
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exc_set.discard(exc_name)
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last_exc = exc
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last_depth = depth
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finally:
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inheritance_tree.close()
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self.assertEqual(len(exc_set), 0, "%s not accounted for" % exc_set)
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interface_tests = ("length", "args", "message", "str", "unicode", "repr",
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"indexing")
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def interface_test_driver(self, results):
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for test_name, (given, expected) in zip(self.interface_tests, results):
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self.assertEqual(given, expected, "%s: %s != %s" % (test_name,
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given, expected))
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@ignore_deprecation_warnings
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def test_interface_single_arg(self):
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# Make sure interface works properly when given a single argument
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arg = "spam"
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exc = Exception(arg)
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results = ([len(exc.args), 1], [exc.args[0], arg], [exc.message, arg],
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[str(exc), str(arg)], [unicode(exc), unicode(arg)],
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[repr(exc), exc.__class__.__name__ + repr(exc.args)],
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[exc[0], arg])
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self.interface_test_driver(results)
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@ignore_deprecation_warnings
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def test_interface_multi_arg(self):
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# Make sure interface correct when multiple arguments given
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arg_count = 3
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args = tuple(range(arg_count))
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exc = Exception(*args)
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results = ([len(exc.args), arg_count], [exc.args, args],
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[exc.message, ''], [str(exc), str(args)],
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[unicode(exc), unicode(args)],
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[repr(exc), exc.__class__.__name__ + repr(exc.args)],
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[exc[-1], args[-1]])
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self.interface_test_driver(results)
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@ignore_deprecation_warnings
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def test_interface_no_arg(self):
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# Make sure that with no args that interface is correct
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exc = Exception()
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results = ([len(exc.args), 0], [exc.args, tuple()],
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[exc.message, ''],
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[str(exc), ''], [unicode(exc), u''],
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[repr(exc), exc.__class__.__name__ + '()'], [True, True])
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self.interface_test_driver(results)
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def test_message_deprecation(self):
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# As of Python 2.6, BaseException.message is deprecated.
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with check_warnings(("", DeprecationWarning)):
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BaseException().message
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class UsageTests(unittest.TestCase):
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"""Test usage of exceptions"""
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def raise_fails(self, object_):
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"""Make sure that raising 'object_' triggers a TypeError."""
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try:
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raise object_
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except TypeError:
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return # What is expected.
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self.fail("TypeError expected for raising %s" % type(object_))
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def catch_fails(self, object_):
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"""Catching 'object_' should raise a TypeError."""
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try:
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try:
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raise StandardError
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except object_:
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pass
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except TypeError:
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pass
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except StandardError:
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self.fail("TypeError expected when catching %s" % type(object_))
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try:
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try:
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raise StandardError
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except (object_,):
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pass
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except TypeError:
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return
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except StandardError:
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self.fail("TypeError expected when catching %s as specified in a "
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"tuple" % type(object_))
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@ignore_deprecation_warnings
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def test_raise_classic(self):
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# Raising a classic class is okay (for now).
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class ClassicClass:
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pass
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try:
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raise ClassicClass
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except ClassicClass:
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pass
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except:
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self.fail("unable to raise classic class")
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try:
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raise ClassicClass()
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except ClassicClass:
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pass
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except:
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self.fail("unable to raise classic class instance")
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def test_raise_new_style_non_exception(self):
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# You cannot raise a new-style class that does not inherit from
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# BaseException; the ability was not possible until BaseException's
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# introduction so no need to support new-style objects that do not
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# inherit from it.
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class NewStyleClass(object):
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pass
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self.raise_fails(NewStyleClass)
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self.raise_fails(NewStyleClass())
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def test_raise_string(self):
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# Raising a string raises TypeError.
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self.raise_fails("spam")
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def test_catch_string(self):
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# Catching a string should trigger a DeprecationWarning.
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with warnings.catch_warnings():
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warnings.resetwarnings()
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warnings.filterwarnings("error")
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str_exc = "spam"
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with self.assertRaises(DeprecationWarning):
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try:
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raise StandardError
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except str_exc:
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pass
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# Make sure that even if the string exception is listed in a tuple
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# that a warning is raised.
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with self.assertRaises(DeprecationWarning):
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try:
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raise StandardError
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except (AssertionError, str_exc):
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pass
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def test_main():
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run_unittest(ExceptionClassTests, UsageTests)
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if __name__ == '__main__':
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test_main()
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