Python test.support.captured_output() Examples

def test_3611(self):
        # A re-raised exception in a __del__ caused the __context__
        # to be cleared
        class C:
            def __del__(self):
                try:
                    1/0
                except:
                    raise

        def f():
            x = C()
            try:
                try:
                    x.x
                except AttributeError:
                    del x
                    raise TypeError
            except Exception as e:
                self.assertNotEqual(e.__context__, None)
                self.assertIsInstance(e.__context__, AttributeError)

        with support.captured_output("stderr"):
            f() 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.TextIOWrapper(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s)

    # Systematic tests of the text I/O API 

def test_show_warning_output(self):
        # With showarning() missing, make sure that output is okay.
        text = 'test show_warning'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                warning_tests.inner(text)
                result = stream.getvalue()
        self.assertEqual(result.count('\n'), 2,
                             "Too many newlines in %r" % result)
        first_line, second_line = result.split('\n', 1)
        expected_file = os.path.splitext(warning_tests.__file__)[0] + '.py'
        first_line_parts = first_line.rsplit(':', 3)
        path, line, warning_class, message = first_line_parts
        line = int(line)
        self.assertEqual(expected_file, path)
        self.assertEqual(warning_class, ' ' + UserWarning.__name__)
        self.assertEqual(message, ' ' + text)
        expected_line = '  ' + linecache.getline(path, line).strip() + '\n'
        assert expected_line
        self.assertEqual(second_line, expected_line) 

def test_save_exception_state_on_error(self):
        # See issue #14474
        def task():
            started.release()
            raise SyntaxError
        def mywrite(self, *args):
            try:
                raise ValueError
            except ValueError:
                pass
            real_write(self, *args)
        c = thread._count()
        started = thread.allocate_lock()
        with support.captured_output("stderr") as stderr:
            real_write = stderr.write
            stderr.write = mywrite
            started.acquire()
            with support.wait_threads_exit():
                thread.start_new_thread(task, ())
                started.acquire()
        self.assertIn("Traceback", stderr.getvalue()) 

def test_3611(self):
        # A re-raised exception in a __del__ caused the __context__
        # to be cleared
        class C:
            def __del__(self):
                try:
                    1/0
                except:
                    raise

        def f():
            x = C()
            try:
                try:
                    x.x
                except AttributeError:
                    del x
                    raise TypeError
            except Exception as e:
                self.assertNotEqual(e.__context__, None)
                self.assertIsInstance(e.__context__, AttributeError)

        with support.captured_output("stderr"):
            f() 

def test_save_exception_state_on_error(self):
        # See issue #14474
        def task():
            started.release()
            raise SyntaxError
        def mywrite(self, *args):
            try:
                raise ValueError
            except ValueError:
                pass
            real_write(self, *args)
        c = thread._count()
        started = thread.allocate_lock()
        with support.captured_output("stderr") as stderr:
            real_write = stderr.write
            stderr.write = mywrite
            started.acquire()
            thread.start_new_thread(task, ())
            started.acquire()
            while thread._count() > c:
                time.sleep(0.01)
        self.assertIn("Traceback", stderr.getvalue()) 

def test_save_exception_state_on_error(self):
        # See issue #14474
        def task():
            started.release()
            raise SyntaxError
        def mywrite(self, *args):
            try:
                raise ValueError
            except ValueError:
                pass
            real_write(self, *args)
        c = thread._count()
        started = thread.allocate_lock()
        with support.captured_output("stderr") as stderr:
            real_write = stderr.write
            stderr.write = mywrite
            started.acquire()
            thread.start_new_thread(task, ())
            started.acquire()
            while thread._count() > c:
                time.sleep(0.01)
        self.assertIn("Traceback", stderr.getvalue()) 

def test_3611(self):
        # A re-raised exception in a __del__ caused the __context__
        # to be cleared
        class C:
            def __del__(self):
                try:
                    1/0
                except:
                    raise

        def f():
            x = C()
            try:
                try:
                    x.x
                except AttributeError:
                    del x
                    raise TypeError
            except Exception as e:
                self.assertNotEqual(e.__context__, None)
                self.assertIsInstance(e.__context__, AttributeError)

        with support.captured_output("stderr"):
            f() 

def test_show_warning_output(self):
        # With showarning() missing, make sure that output is okay.
        text = 'test show_warning'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                warning_tests.inner(text)
                result = stream.getvalue()
        self.assertEqual(result.count('\n'), 2,
                             "Too many newlines in %r" % result)
        first_line, second_line = result.split('\n', 1)
        expected_file = os.path.splitext(warning_tests.__file__)[0] + '.py'
        first_line_parts = first_line.rsplit(':', 3)
        path, line, warning_class, message = first_line_parts
        line = int(line)
        self.assertEqual(expected_file, path)
        self.assertEqual(warning_class, ' ' + UserWarning.__name__)
        self.assertEqual(message, ' ' + text)
        expected_line = '  ' + linecache.getline(path, line).strip() + '\n'
        assert expected_line
        self.assertEqual(second_line, expected_line) 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.TextIOWrapper(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s)

    # Systematic tests of the text I/O API 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.TextIOWrapper(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s)

    # Systematic tests of the text I/O API 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.TextIOWrapper(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s)

    # Systematic tests of the text I/O API 

def test_show_warning_output(self):
        # With showarning() missing, make sure that output is okay.
        text = 'test show_warning'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                warning_tests.inner(text)
                result = stream.getvalue()
        self.assertEqual(result.count('\n'), 2,
                             "Too many newlines in %r" % result)
        first_line, second_line = result.split('\n', 1)
        expected_file = os.path.splitext(warning_tests.__file__)[0] + '.py'
        first_line_parts = first_line.rsplit(':', 3)
        path, line, warning_class, message = first_line_parts
        line = int(line)
        self.assertEqual(expected_file, path)
        self.assertEqual(warning_class, ' ' + UserWarning.__name__)
        self.assertEqual(message, ' ' + text)
        expected_line = '  ' + linecache.getline(path, line).strip() + '\n'
        assert expected_line
        self.assertEqual(second_line, expected_line) 

def test_save_exception_state_on_error(self):
        # See issue #14474
        def task():
            started.release()
            raise SyntaxError
        def mywrite(self, *args):
            try:
                raise ValueError
            except ValueError:
                pass
            real_write(self, *args)
        c = thread._count()
        started = thread.allocate_lock()
        with support.captured_output("stderr") as stderr:
            real_write = stderr.write
            stderr.write = mywrite
            started.acquire()
            thread.start_new_thread(task, ())
            started.acquire()
            while thread._count() > c:
                time.sleep(0.01)
        self.assertIn("Traceback", stderr.getvalue()) 

def test_3611(self):
        # A re-raised exception in a __del__ caused the __context__
        # to be cleared
        class C:
            def __del__(self):
                try:
                    1/0
                except:
                    raise

        def f():
            x = C()
            try:
                try:
                    x.x
                except AttributeError:
                    del x
                    raise TypeError
            except Exception as e:
                self.assertNotEqual(e.__context__, None)
                self.assertIsInstance(e.__context__, AttributeError)

        with support.captured_output("stderr"):
            f() 

def test_stack_format(self):
        # Verify _stack functions. Note we have to use _getframe(1) to
        # compare them without this frame appearing in the output
        with captured_output("stderr") as ststderr:
            traceback.print_stack(sys._getframe(1))
        stfile = StringIO()
        traceback.print_stack(sys._getframe(1), file=stfile)
        self.assertEqual(ststderr.getvalue(), stfile.getvalue())

        stfmt = traceback.format_stack(sys._getframe(1))

        self.assertEqual(ststderr.getvalue(), "".join(stfmt)) 

def test_showwarning_missing(self):
        # Test that showwarning() missing is okay.
        text = 'del showwarning test'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                self.module.warn(text)
                result = stream.getvalue()
        self.assertIn(text, result) 

def test_showwarning_not_callable(self):
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            self.module.showwarning = print
            with support.captured_output('stdout'):
                self.module.warn('Warning!')
            self.module.showwarning = 23
            self.assertRaises(TypeError, self.module.warn, "Warning!") 

def test_print_function(self):
        with support.captured_output("stderr") as s:
            print("foo", file=sys.stderr)
        self.assertEqual(s.getvalue(), "foo\n") 

def test_showwarning_not_callable(self):
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            self.module.showwarning = print
            with support.captured_output('stdout'):
                self.module.warn('Warning!')
            self.module.showwarning = 23
            self.assertRaises(TypeError, self.module.warn, "Warning!") 

def test_showwarnmsg_missing(self):
        # Test that _showwarnmsg() missing is okay.
        text = 'del _showwarnmsg test'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)

            show = self.module._showwarnmsg
            try:
                del self.module._showwarnmsg
                with support.captured_output('stderr') as stream:
                    self.module.warn(text)
                    result = stream.getvalue()
            finally:
                self.module._showwarnmsg = show
        self.assertIn(text, result) 

def test_bug_7244(self):

        class Repeater:
            # this class is similar to itertools.repeat
            def __init__(self, o, t, e):
                self.o = o
                self.t = int(t)
                self.e = e
            def __iter__(self): # its iterator is itself
                return self
            def __next__(self):
                if self.t > 0:
                    self.t -= 1
                    return self.o
                else:
                    raise self.e

        # Formerly this code in would fail in debug mode
        # with Undetected Error and Stop Iteration
        r1 = Repeater(1, 3, StopIteration)
        r2 = Repeater(2, 4, StopIteration)
        def run(r1, r2):
            result = []
            for i, j in zip_longest(r1, r2, fillvalue=0):
                with support.captured_output('stdout'):
                    print((i, j))
                result.append((i, j))
            return result
        self.assertEqual(run(r1, r2), [(1,2), (1,2), (1,2), (0,2)])

        # Formerly, the RuntimeError would be lost
        # and StopIteration would stop as expected
        r1 = Repeater(1, 3, RuntimeError)
        r2 = Repeater(2, 4, StopIteration)
        it = zip_longest(r1, r2, fillvalue=0)
        self.assertEqual(next(it), (1, 2))
        self.assertEqual(next(it), (1, 2))
        self.assertEqual(next(it), (1, 2))
        self.assertRaises(RuntimeError, next, it) 

def test_stack_format(self):
        # Verify _stack functions. Note we have to use _getframe(1) to
        # compare them without this frame appearing in the output
        with captured_output("stderr") as ststderr:
            traceback.print_stack(sys._getframe(1))
        stfile = StringIO()
        traceback.print_stack(sys._getframe(1), file=stfile)
        self.assertEqual(ststderr.getvalue(), stfile.getvalue())

        stfmt = traceback.format_stack(sys._getframe(1))

        self.assertEqual(ststderr.getvalue(), "".join(stfmt)) 

def test_showwarning_missing(self):
        # Test that showwarning() missing is okay.
        text = 'del showwarning test'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                self.module.warn(text)
                result = stream.getvalue()
        self.assertIn(text, result) 

def get_report(self, e):
        e = self.get_exception(e)
        s = ''.join(
            traceback.format_exception(type(e), e, e.__traceback__))
        with captured_output("stderr") as sio:
            traceback.print_exception(type(e), e, e.__traceback__)
        self.assertEqual(sio.getvalue(), s)
        return s 

def get_report(self, e):
        from _testcapi import exception_print
        e = self.get_exception(e)
        with captured_output("stderr") as s:
            exception_print(e)
        return s.getvalue() 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.tp(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s) 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.tp(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s) 

def test_error_through_destructor(self):
        # Test that the exception state is not modified by a destructor,
        # even if close() fails.
        rawio = self.CloseFailureIO()
        def f():
            self.tp(rawio).xyzzy
        with support.captured_output("stderr") as s:
            self.assertRaises(AttributeError, f)
        s = s.getvalue().strip()
        if s:
            # The destructor *may* have printed an unraisable error, check it
            self.assertEqual(len(s.splitlines()), 1)
            self.assertTrue(s.startswith("Exception OSError: "), s)
            self.assertTrue(s.endswith(" ignored"), s) 

def test_showwarning_missing(self):
        # Test that showwarning() missing is okay.
        text = 'del showwarning test'
        with original_warnings.catch_warnings(module=self.module):
            self.module.filterwarnings("always", category=UserWarning)
            del self.module.showwarning
            with support.captured_output('stderr') as stream:
                self.module.warn(text)
                result = stream.getvalue()
        self.assertIn(text, result)