Method do_test

Lib/test/test_traceback.py:428–456

(firstlines, message, charset, lineno)

        output_encoding = str(stdout, 'ascii').splitlines()[0]

        def do_test(firstlines, message, charset, lineno):
            # Raise the message in a subprocess, and catch the output
            try:
                with open(TESTFN, "w", encoding=charset) as output:
                    output.write("""{0}if 1:
                        import traceback;
                        raise RuntimeError('{1}')
                        """.format(firstlines, message))

                process = subprocess.Popen([sys.executable, TESTFN],
                    stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
                stdout, stderr = process.communicate()
                stdout = stdout.decode(output_encoding).splitlines()
            finally:
                unlink(TESTFN)

            # The source lines are encoded with the 'backslashreplace' handler
            encoded_message = message.encode(output_encoding,
                                             'backslashreplace')
            # and we just decoded them with the output_encoding.
            message_ascii = encoded_message.decode(output_encoding)

            err_line = "raise RuntimeError('{0}')".format(message_ascii)
            err_msg = "RuntimeError: {0}".format(message_ascii)

            self.assertIn("line %s" % lineno, stdout[1])
            self.assertEndsWith(stdout[2], err_line)
            actual_err_msg = stdout[3]
            self.assertEqual(actual_err_msg, err_msg)

        do_test("", "foo", "ascii", 3)
        for charset in ("ascii", "iso-8859-1", "utf-8", "GBK"):