test_traceback.py 文件源码

def test_traceback_format(self):
        from _testcapi import traceback_print
        try:
            raise KeyError('blah')
        except KeyError:
            type_, value, tb = sys.exc_info()
            traceback_fmt = 'Traceback (most recent call last):\n' + \
                            ''.join(traceback.format_tb(tb))
            file_ = StringIO()
            traceback_print(tb, file_)
            python_fmt  = file_.getvalue()
        else:
            raise Error("unable to create test traceback string")

        # Make sure that Python and the traceback module format the same thing
        self.assertEqual(traceback_fmt, python_fmt)

        # Make sure that the traceback is properly indented.
        tb_lines = python_fmt.splitlines()
        self.assertEqual(len(tb_lines), 3)
        banner, location, source_line = tb_lines
        self.assertTrue(banner.startswith('Traceback'))
        self.assertTrue(location.startswith('  File'))
        self.assertTrue(source_line.startswith('    raise'))