# Python test set -- part 5, built-in exceptions import os import sys import unittest import pickle import weakref import errno from test.support import (TESTFN, captured_output, check_impl_detail, check_warnings, cpython_only, gc_collect, run_unittest, no_tracing, unlink) class NaiveException(Exception): def __init__(self, x): self.x = x class SlottedNaiveException(Exception): __slots__ = ('x',) def __init__(self, x): self.x = x # XXX This is not really enough, each *operation* should be tested! class ExceptionTests(unittest.TestCase): def raise_catch(self, exc, excname): try: raise exc("spam") except exc as err: buf1 = str(err) try: raise exc("spam") except exc as err: buf2 = str(err) self.assertEqual(buf1, buf2) self.assertEqual(exc.__name__, excname) def testRaising(self): self.raise_catch(AttributeError, "AttributeError") self.assertRaises(AttributeError, getattr, sys, "undefined_attribute") self.raise_catch(EOFError, "EOFError") fp = open(TESTFN, 'w') fp.close() fp = open(TESTFN, 'r') savestdin = sys.stdin try: try: import marshal marshal.loads(b'') except EOFError: pass finally: sys.stdin = savestdin fp.close() unlink(TESTFN) self.raise_catch(OSError, "OSError") self.assertRaises(OSError, open, 'this file does not exist', 'r') self.raise_catch(ImportError, "ImportError") self.assertRaises(ImportError, __import__, "undefined_module") self.raise_catch(IndexError, "IndexError") x = [] self.assertRaises(IndexError, x.__getitem__, 10) self.raise_catch(KeyError, "KeyError") x = {} self.assertRaises(KeyError, x.__getitem__, 'key') self.raise_catch(KeyboardInterrupt, "KeyboardInterrupt") self.raise_catch(MemoryError, "MemoryError") self.raise_catch(NameError, "NameError") try: x = undefined_variable except NameError: pass self.raise_catch(OverflowError, "OverflowError") x = 1 for dummy in range(128): x += x # this simply shouldn't blow up self.raise_catch(RuntimeError, "RuntimeError") self.raise_catch(SyntaxError, "SyntaxError") try: exec('/\n') except SyntaxError: pass self.raise_catch(IndentationError, "IndentationError") self.raise_catch(TabError, "TabError") try: compile("try:\n\t1/0\n \t1/0\nfinally:\n pass\n", '', 'exec') except TabError: pass else: self.fail("TabError not raised") self.raise_catch(SystemError, "SystemError") self.raise_catch(SystemExit, "SystemExit") self.assertRaises(SystemExit, sys.exit, 0) self.raise_catch(TypeError, "TypeError") try: [] + () except TypeError: pass self.raise_catch(ValueError, "ValueError") self.assertRaises(ValueError, chr, 17<<16) self.raise_catch(ZeroDivisionError, "ZeroDivisionError") try: x = 1/0 except ZeroDivisionError: pass self.raise_catch(Exception, "Exception") try: x = 1/0 except Exception as e: pass def testSyntaxErrorMessage(self): # make sure the right exception message is raised for each of # these code fragments def ckmsg(src, msg): try: compile(src, '', 'exec') except SyntaxError as e: if e.msg != msg: self.fail("expected %s, got %s" % (msg, e.msg)) else: self.fail("failed to get expected SyntaxError") s = '''while 1: try: pass finally: continue''' if not sys.platform.startswith('java'): ckmsg(s, "'continue' not supported inside 'finally' clause") s = '''if 1: try: continue except: pass''' ckmsg(s, "'continue' not properly in loop") ckmsg("continue\n", "'continue' not properly in loop") @cpython_only def testSettingException(self): # test that setting an exception at the C level works even if the # exception object can't be constructed. class BadException(Exception): def __init__(self_): raise RuntimeError("can't instantiate BadException") class InvalidException: pass def test_capi1(): import _testcapi try: _testcapi.raise_exception(BadException, 1) except TypeError as err: exc, err, tb = sys.exc_info() co = tb.tb_frame.f_code self.assertEqual(co.co_name, "test_capi1") self.assertTrue(co.co_filename.endswith('test_exceptions.py')) else: self.fail("Expected exception") def test_capi2(): import _testcapi try: _testcapi.raise_exception(BadException, 0) except RuntimeError as err: exc, err, tb = sys.exc_info() co = tb.tb_frame.f_code self.assertEqual(co.co_name, "__init__") self.assertTrue(co.co_filename.endswith('test_exceptions.py')) co2 = tb.tb_frame.f_back.f_code self.assertEqual(co2.co_name, "test_capi2") else: self.fail("Expected exception") def test_capi3(): import _testcapi self.assertRaises(SystemError, _testcapi.raise_exception, InvalidException, 1) if not sys.platform.startswith('java'): test_capi1() test_capi2() test_capi3() def test_WindowsError(self): try: WindowsError except NameError: pass else: self.assertIs(WindowsError, OSError) self.assertEqual(str(OSError(1001)), "1001") self.assertEqual(str(OSError(1001, "message")), "[Errno 1001] message") # POSIX errno (9 aka EBADF) is untranslated w = OSError(9, 'foo', 'bar') self.assertEqual(w.errno, 9) self.assertEqual(w.winerror, None) self.assertEqual(str(w), "[Errno 9] foo: 'bar'") # ERROR_PATH_NOT_FOUND (win error 3) becomes ENOENT (2) w = OSError(0, 'foo', 'bar', 3) self.assertEqual(w.errno, 2) self.assertEqual(w.winerror, 3) self.assertEqual(w.strerror, 'foo') self.assertEqual(w.filename, 'bar') self.assertEqual(str(w), "[WinError 3] foo: 'bar'") # Unknown win error becomes EINVAL (22) w = OSError(0, 'foo', None, 1001) self.assertEqual(w.errno, 22) self.assertEqual(w.winerror, 1001) self.assertEqual(w.strerror, 'foo') self.assertEqual(w.filename, None) self.assertEqual(str(w), "[WinError 1001] foo") # Non-numeric "errno" w = OSError('bar', 'foo') self.assertEqual(w.errno, 'bar') self.assertEqual(w.winerror, None) self.assertEqual(w.strerror, 'foo') self.assertEqual(w.filename, None) def testAttributes(self): # test that exception attributes are happy exceptionList = [ (BaseException, (), {'args' : ()}), (BaseException, (1, ), {'args' : (1,)}), (BaseException, ('foo',), {'args' : ('foo',)}), (BaseException, ('foo', 1), {'args' : ('foo', 1)}), (SystemExit, ('foo',), {'args' : ('foo',), 'code' : 'foo'}), (IOError, ('foo',), {'args' : ('foo',), 'filename' : None, 'errno' : None, 'strerror' : None}), (IOError, ('foo', 'bar'), {'args' : ('foo', 'bar'), 'filename' : None, 'errno' : 'foo', 'strerror' : 'bar'}), (IOError, ('foo', 'bar', 'baz'), {'args' : ('foo', 'bar'), 'filename' : 'baz', 'errno' : 'foo', 'strerror' : 'bar'}), (IOError, ('foo', 'bar', 'baz', 'quux'), {'args' : ('foo', 'bar', 'baz', 'quux')}), (OSError, ('errnoStr', 'strErrorStr', 'filenameStr'), {'args' : ('errnoStr', 'strErrorStr'), 'strerror' : 'strErrorStr', 'errno' : 'errnoStr', 'filename' : 'filenameStr'}), (OSError, (1, 'strErrorStr', 'filenameStr'), {'args' : (1, 'strErrorStr'), 'errno' : 1, 'strerror' : 'strErrorStr', 'filename' : 'filenameStr'}), (SyntaxError, (), {'msg' : None, 'text' : None, 'filename' : None, 'lineno' : None, 'offset' : None, 'print_file_and_line' : None}), (SyntaxError, ('msgStr',), {'args' : ('msgStr',), 'text' : None, 'print_file_and_line' : None, 'msg' : 'msgStr', 'filename' : None, 'lineno' : None, 'offset' : None}), (SyntaxError, ('msgStr', ('filenameStr', 'linenoStr', 'offsetStr', 'textStr')), {'offset' : 'offsetStr', 'text' : 'textStr', 'args' : ('msgStr', ('filenameStr', 'linenoStr', 'offsetStr', 'textStr')), 'print_file_and_line' : None, 'msg' : 'msgStr', 'filename' : 'filenameStr', 'lineno' : 'linenoStr'}), (SyntaxError, ('msgStr', 'filenameStr', 'linenoStr', 'offsetStr', 'textStr', 'print_file_and_lineStr'), {'text' : None, 'args' : ('msgStr', 'filenameStr', 'linenoStr', 'offsetStr', 'textStr', 'print_file_and_lineStr'), 'print_file_and_line' : None, 'msg' : 'msgStr', 'filename' : None, 'lineno' : None, 'offset' : None}), (UnicodeError, (), {'args' : (),}), (UnicodeEncodeError, ('ascii', 'a', 0, 1, 'ordinal not in range'), {'args' : ('ascii', 'a', 0, 1, 'ordinal not in range'), 'encoding' : 'ascii', 'object' : 'a', 'start' : 0, 'reason' : 'ordinal not in range'}), (UnicodeDecodeError, ('ascii', bytearray(b'\xff'), 0, 1, 'ordinal not in range'), {'args' : ('ascii', bytearray(b'\xff'), 0, 1, 'ordinal not in range'), 'encoding' : 'ascii', 'object' : b'\xff', 'start' : 0, 'reason' : 'ordinal not in range'}), (UnicodeDecodeError, ('ascii', b'\xff', 0, 1, 'ordinal not in range'), {'args' : ('ascii', b'\xff', 0, 1, 'ordinal not in range'), 'encoding' : 'ascii', 'object' : b'\xff', 'start' : 0, 'reason' : 'ordinal not in range'}), (UnicodeTranslateError, ("\u3042", 0, 1, "ouch"), {'args' : ('\u3042', 0, 1, 'ouch'), 'object' : '\u3042', 'reason' : 'ouch', 'start' : 0, 'end' : 1}), (NaiveException, ('foo',), {'args': ('foo',), 'x': 'foo'}), (SlottedNaiveException, ('foo',), {'args': ('foo',), 'x': 'foo'}), ] try: # More tests are in test_WindowsError exceptionList.append( (WindowsError, (1, 'strErrorStr', 'filenameStr'), {'args' : (1, 'strErrorStr'), 'strerror' : 'strErrorStr', 'winerror' : None, 'errno' : 1, 'filename' : 'filenameStr'}) ) except NameError: pass for exc, args, expected in exceptionList: try: e = exc(*args) except: print("\nexc=%r, args=%r" % (exc, args), file=sys.stderr) raise else: # Verify module name if not type(e).__name__.endswith('NaiveException'): self.assertEqual(type(e).__module__, 'builtins') # Verify no ref leaks in Exc_str() s = str(e) for checkArgName in expected: value = getattr(e, checkArgName) self.assertEqual(repr(value), repr(expected[checkArgName]), '%r.%s == %r, expected %r' % ( e, checkArgName, value, expected[checkArgName])) # test for pickling support for p in [pickle]: for protocol in range(p.HIGHEST_PROTOCOL + 1): s = p.dumps(e, protocol) new = p.loads(s) for checkArgName in expected: got = repr(getattr(new, checkArgName)) want = repr(expected[checkArgName]) self.assertEqual(got, want, 'pickled "%r", attribute "%s' % (e, checkArgName)) def testWithTraceback(self): try: raise IndexError(4) except: tb = sys.exc_info()[2] e = BaseException().with_traceback(tb) self.assertIsInstance(e, BaseException) self.assertEqual(e.__traceback__, tb) e = IndexError(5).with_traceback(tb) self.assertIsInstance(e, IndexError) self.assertEqual(e.__traceback__, tb) class MyException(Exception): pass e = MyException().with_traceback(tb) self.assertIsInstance(e, MyException) self.assertEqual(e.__traceback__, tb) def testInvalidTraceback(self): try: Exception().__traceback__ = 5 except TypeError as e: self.assertIn("__traceback__ must be a traceback", str(e)) else: self.fail("No exception raised") def testInvalidAttrs(self): self.assertRaises(TypeError, setattr, Exception(), '__cause__', 1) self.assertRaises(TypeError, delattr, Exception(), '__cause__') self.assertRaises(TypeError, setattr, Exception(), '__context__', 1) self.assertRaises(TypeError, delattr, Exception(), '__context__') def testNoneClearsTracebackAttr(self): try: raise IndexError(4) except: tb = sys.exc_info()[2] e = Exception() e.__traceback__ = tb e.__traceback__ = None self.assertEqual(e.__traceback__, None) def testChainingAttrs(self): e = Exception() self.assertIsNone(e.__context__) self.assertIsNone(e.__cause__) e = TypeError() self.assertIsNone(e.__context__) self.assertIsNone(e.__cause__) class MyException(OSError): pass e = MyException() self.assertIsNone(e.__context__) self.assertIsNone(e.__cause__) def testChainingDescriptors(self): try: raise Exception() except Exception as exc: e = exc self.assertIsNone(e.__context__) self.assertIsNone(e.__cause__) self.assertFalse(e.__suppress_context__) e.__context__ = NameError() e.__cause__ = None self.assertIsInstance(e.__context__, NameError) self.assertIsNone(e.__cause__) self.assertTrue(e.__suppress_context__) e.__suppress_context__ = False self.assertFalse(e.__suppress_context__) def testKeywordArgs(self): # test that builtin exception don't take keyword args, # but user-defined subclasses can if they want self.assertRaises(TypeError, BaseException, a=1) class DerivedException(BaseException): def __init__(self, fancy_arg): BaseException.__init__(self) self.fancy_arg = fancy_arg x = DerivedException(fancy_arg=42) self.assertEqual(x.fancy_arg, 42) @no_tracing def testInfiniteRecursion(self): def f(): return f() self.assertRaises(RuntimeError, f) def g(): try: return g() except ValueError: return -1 self.assertRaises(RuntimeError, g) def test_str(self): # Make sure both instances and classes have a str representation. self.assertTrue(str(Exception)) self.assertTrue(str(Exception('a'))) self.assertTrue(str(Exception('a', 'b'))) def testExceptionCleanupNames(self): # Make sure the local variable bound to the exception instance by # an "except" statement is only visible inside the except block. try: raise Exception() except Exception as e: self.assertTrue(e) del e self.assertNotIn('e', locals()) def testExceptionCleanupState(self): # Make sure exception state is cleaned up as soon as the except # block is left. See #2507 class MyException(Exception): def __init__(self, obj): self.obj = obj class MyObj: pass def inner_raising_func(): # Create some references in exception value and traceback local_ref = obj raise MyException(obj) # Qualified "except" with "as" obj = MyObj() wr = weakref.ref(obj) try: inner_raising_func() except MyException as e: pass obj = None obj = wr() self.assertTrue(obj is None, "%s" % obj) # Qualified "except" without "as" obj = MyObj() wr = weakref.ref(obj) try: inner_raising_func() except MyException: pass obj = None obj = wr() self.assertTrue(obj is None, "%s" % obj) # Bare "except" obj = MyObj() wr = weakref.ref(obj) try: inner_raising_func() except: pass obj = None obj = wr() self.assertTrue(obj is None, "%s" % obj) # "except" with premature block leave obj = MyObj() wr = weakref.ref(obj) for i in [0]: try: inner_raising_func() except: break obj = None obj = wr() self.assertTrue(obj is None, "%s" % obj) # "except" block raising another exception obj = MyObj() wr = weakref.ref(obj) try: try: inner_raising_func() except: raise KeyError except KeyError as e: # We want to test that the except block above got rid of # the exception raised in inner_raising_func(), but it # also ends up in the __context__ of the KeyError, so we # must clear the latter manually for our test to succeed. e.__context__ = None obj = None obj = wr() # guarantee no ref cycles on CPython (don't gc_collect) if check_impl_detail(cpython=False): gc_collect() self.assertTrue(obj is None, "%s" % obj) # Some complicated construct obj = MyObj() wr = weakref.ref(obj) try: inner_raising_func() except MyException: try: try: raise finally: raise except MyException: pass obj = None if check_impl_detail(cpython=False): gc_collect() obj = wr() self.assertTrue(obj is None, "%s" % obj) # Inside an exception-silencing "with" block class Context: def __enter__(self): return self def __exit__ (self, exc_type, exc_value, exc_tb): return True obj = MyObj() wr = weakref.ref(obj) with Context(): inner_raising_func() obj = None if check_impl_detail(cpython=False): gc_collect() obj = wr() self.assertTrue(obj is None, "%s" % obj) def test_exception_target_in_nested_scope(self): # issue 4617: This used to raise a SyntaxError # "can not delete variable 'e' referenced in nested scope" def print_error(): e try: something except Exception as e: print_error() # implicit "del e" here def test_generator_leaking(self): # Test that generator exception state doesn't leak into the calling # frame def yield_raise(): try: raise KeyError("caught") except KeyError: yield sys.exc_info()[0] yield sys.exc_info()[0] yield sys.exc_info()[0] g = yield_raise() self.assertEqual(next(g), KeyError) self.assertEqual(sys.exc_info()[0], None) self.assertEqual(next(g), KeyError) self.assertEqual(sys.exc_info()[0], None) self.assertEqual(next(g), None) # Same test, but inside an exception handler try: raise TypeError("foo") except TypeError: g = yield_raise() self.assertEqual(next(g), KeyError) self.assertEqual(sys.exc_info()[0], TypeError) self.assertEqual(next(g), KeyError) self.assertEqual(sys.exc_info()[0], TypeError) self.assertEqual(next(g), TypeError) del g self.assertEqual(sys.exc_info()[0], TypeError) def test_generator_leaking2(self): # See issue 12475. def g(): yield try: raise RuntimeError except RuntimeError: it = g() next(it) try: next(it) except StopIteration: pass self.assertEqual(sys.exc_info(), (None, None, None)) def test_generator_doesnt_retain_old_exc(self): def g(): self.assertIsInstance(sys.exc_info()[1], RuntimeError) yield self.assertEqual(sys.exc_info(), (None, None, None)) it = g() try: raise RuntimeError except RuntimeError: next(it) self.assertRaises(StopIteration, next, it) def test_generator_finalizing_and_exc_info(self): # See #7173 def simple_gen(): yield 1 def run_gen(): gen = simple_gen() try: raise RuntimeError except RuntimeError: return next(gen) run_gen() gc_collect() self.assertEqual(sys.exc_info(), (None, None, None)) def _check_generator_cleanup_exc_state(self, testfunc): # Issue #12791: exception state is cleaned up as soon as a generator # is closed (reference cycles are broken). class MyException(Exception): def __init__(self, obj): self.obj = obj class MyObj: pass def raising_gen(): try: raise MyException(obj) except MyException: yield obj = MyObj() wr = weakref.ref(obj) g = raising_gen() next(g) testfunc(g) g = obj = None obj = wr() self.assertIs(obj, None) def test_generator_throw_cleanup_exc_state(self): def do_throw(g): try: g.throw(RuntimeError()) except RuntimeError: pass self._check_generator_cleanup_exc_state(do_throw) def test_generator_close_cleanup_exc_state(self): def do_close(g): g.close() self._check_generator_cleanup_exc_state(do_close) def test_generator_del_cleanup_exc_state(self): def do_del(g): g = None self._check_generator_cleanup_exc_state(do_del) def test_generator_next_cleanup_exc_state(self): def do_next(g): try: next(g) except StopIteration: pass else: self.fail("should have raised StopIteration") self._check_generator_cleanup_exc_state(do_next) def test_generator_send_cleanup_exc_state(self): def do_send(g): try: g.send(None) except StopIteration: pass else: self.fail("should have raised StopIteration") self._check_generator_cleanup_exc_state(do_send) def test_3114(self): # Bug #3114: in its destructor, MyObject retrieves a pointer to # obsolete and/or deallocated objects. class MyObject: def __del__(self): nonlocal e e = sys.exc_info() e = () try: raise Exception(MyObject()) except: pass self.assertEqual(e, (None, None, None)) def testUnicodeChangeAttributes(self): # See issue 7309. This was a crasher. u = UnicodeEncodeError('baz', 'xxxxx', 1, 5, 'foo') self.assertEqual(str(u), "'baz' codec can't encode characters in position 1-4: foo") u.end = 2 self.assertEqual(str(u), "'baz' codec can't encode character '\\x78' in position 1: foo") u.end = 5 u.reason = 0x345345345345345345 self.assertEqual(str(u), "'baz' codec can't encode characters in position 1-4: 965230951443685724997") u.encoding = 4000 self.assertEqual(str(u), "'4000' codec can't encode characters in position 1-4: 965230951443685724997") u.start = 1000 self.assertEqual(str(u), "'4000' codec can't encode characters in position 1000-4: 965230951443685724997") u = UnicodeDecodeError('baz', b'xxxxx', 1, 5, 'foo') self.assertEqual(str(u), "'baz' codec can't decode bytes in position 1-4: foo") u.end = 2 self.assertEqual(str(u), "'baz' codec can't decode byte 0x78 in position 1: foo") u.end = 5 u.reason = 0x345345345345345345 self.assertEqual(str(u), "'baz' codec can't decode bytes in position 1-4: 965230951443685724997") u.encoding = 4000 self.assertEqual(str(u), "'4000' codec can't decode bytes in position 1-4: 965230951443685724997") u.start = 1000 self.assertEqual(str(u), "'4000' codec can't decode bytes in position 1000-4: 965230951443685724997") u = UnicodeTranslateError('xxxx', 1, 5, 'foo') self.assertEqual(str(u), "can't translate characters in position 1-4: foo") u.end = 2 self.assertEqual(str(u), "can't translate character '\\x78' in position 1: foo") u.end = 5 u.reason = 0x345345345345345345 self.assertEqual(str(u), "can't translate characters in position 1-4: 965230951443685724997") u.start = 1000 self.assertEqual(str(u), "can't translate characters in position 1000-4: 965230951443685724997") @no_tracing def test_badisinstance(self): # Bug #2542: if issubclass(e, MyException) raises an exception, # it should be ignored class Meta(type): def __subclasscheck__(cls, subclass): raise ValueError() class MyException(Exception, metaclass=Meta): pass with captured_output("stderr") as stderr: try: raise KeyError() except MyException as e: self.fail("exception should not be a MyException") except KeyError: pass except: self.fail("Should have raised KeyError") else: self.fail("Should have raised KeyError") def g(): try: return g() except RuntimeError: return sys.exc_info() e, v, tb = g() self.assertTrue(isinstance(v, RuntimeError), type(v)) self.assertIn("maximum recursion depth exceeded", str(v)) def test_MemoryError(self): # PyErr_NoMemory always raises the same exception instance. # Check that the traceback is not doubled. import traceback from _testcapi import raise_memoryerror def raiseMemError(): try: raise_memoryerror() except MemoryError as e: tb = e.__traceback__ else: self.fail("Should have raises a MemoryError") return traceback.format_tb(tb) tb1 = raiseMemError() tb2 = raiseMemError() self.assertEqual(tb1, tb2) @cpython_only def test_exception_with_doc(self): import _testcapi doc2 = "This is a test docstring." doc4 = "This is another test docstring." self.assertRaises(SystemError, _testcapi.make_exception_with_doc, "error1") # test basic usage of PyErr_NewException error1 = _testcapi.make_exception_with_doc("_testcapi.error1") self.assertIs(type(error1), type) self.assertTrue(issubclass(error1, Exception)) self.assertIsNone(error1.__doc__) # test with given docstring error2 = _testcapi.make_exception_with_doc("_testcapi.error2", doc2) self.assertEqual(error2.__doc__, doc2) # test with explicit base (without docstring) error3 = _testcapi.make_exception_with_doc("_testcapi.error3", base=error2) self.assertTrue(issubclass(error3, error2)) # test with explicit base tuple class C(object): pass error4 = _testcapi.make_exception_with_doc("_testcapi.error4", doc4, (error3, C)) self.assertTrue(issubclass(error4, error3)) self.assertTrue(issubclass(error4, C)) self.assertEqual(error4.__doc__, doc4) # test with explicit dictionary error5 = _testcapi.make_exception_with_doc("_testcapi.error5", "", error4, {'a': 1}) self.assertTrue(issubclass(error5, error4)) self.assertEqual(error5.a, 1) self.assertEqual(error5.__doc__, "") def test_memory_error_cleanup(self): # Issue #5437: preallocated MemoryError instances should not keep # traceback objects alive. from _testcapi import raise_memoryerror class C: pass wr = None def inner(): nonlocal wr c = C() wr = weakref.ref(c) raise_memoryerror() # We cannot use assertRaises since it manually deletes the traceback try: inner() except MemoryError as e: self.assertNotEqual(wr(), None) else: self.fail("MemoryError not raised") self.assertEqual(wr(), None) @no_tracing def test_recursion_error_cleanup(self): # Same test as above, but with "recursion exceeded" errors class C: pass wr = None def inner(): nonlocal wr c = C() wr = weakref.ref(c) inner() # We cannot use assertRaises since it manually deletes the traceback try: inner() except RuntimeError as e: self.assertNotEqual(wr(), None) else: self.fail("RuntimeError not raised") self.assertEqual(wr(), None) def test_errno_ENOTDIR(self): # Issue #12802: "not a directory" errors are ENOTDIR even on Windows with self.assertRaises(OSError) as cm: os.listdir(__file__) self.assertEqual(cm.exception.errno, errno.ENOTDIR, cm.exception) class ImportErrorTests(unittest.TestCase): def test_attributes(self): # Setting 'name' and 'path' should not be a problem. exc = ImportError('test') self.assertIsNone(exc.name) self.assertIsNone(exc.path) exc = ImportError('test', name='somemodule') self.assertEqual(exc.name, 'somemodule') self.assertIsNone(exc.path) exc = ImportError('test', path='somepath') self.assertEqual(exc.path, 'somepath') self.assertIsNone(exc.name) exc = ImportError('test', path='somepath', name='somename') self.assertEqual(exc.name, 'somename') self.assertEqual(exc.path, 'somepath') def test_non_str_argument(self): # Issue #15778 with check_warnings(('', BytesWarning), quiet=True): arg = b'abc' exc = ImportError(arg) self.assertEqual(str(arg), str(exc)) def test_main(): run_unittest(ExceptionTests, ImportErrorTests) if __name__ == '__main__': unittest.main()