cpython/Lib/test/test_httpservers.py

"""Unittests for the various HTTPServer modules.

Written by Cody A.W. Somerville <cody-somerville@ubuntu.com>,
Josip Dzolonga, and Michael Otteneder for the 2007/08 GHOP contest.
"""

from http.server import BaseHTTPRequestHandler, HTTPServer, \
     SimpleHTTPRequestHandler, CGIHTTPRequestHandler
from http import server

import os
import sys
import re
import base64
import shutil
import urllib.parse
import http.client
import tempfile
from io import BytesIO

import unittest
from test import support
threading = support.import_module('threading')

class NoLogRequestHandler:
    def log_message(self, *args):
        # don't write log messages to stderr
        pass

    def read(self, n=None):
        return ''


class TestServerThread(threading.Thread):
    def __init__(self, test_object, request_handler):
        threading.Thread.__init__(self)
        self.request_handler = request_handler
        self.test_object = test_object

    def run(self):
        self.server = HTTPServer(('localhost', 0), self.request_handler)
        self.test_object.HOST, self.test_object.PORT = self.server.socket.getsockname()
        self.test_object.server_started.set()
        self.test_object = None
        try:
            self.server.serve_forever(0.05)
        finally:
            self.server.server_close()

    def stop(self):
        self.server.shutdown()


class BaseTestCase(unittest.TestCase):
    def setUp(self):
        self._threads = support.threading_setup()
        os.environ = support.EnvironmentVarGuard()
        self.server_started = threading.Event()
        self.thread = TestServerThread(self, self.request_handler)
        self.thread.start()
        self.server_started.wait()

    def tearDown(self):
        self.thread.stop()
        self.thread = None
        os.environ.__exit__()
        support.threading_cleanup(*self._threads)

    def request(self, uri, method='GET', body=None, headers={}):
        self.connection = http.client.HTTPConnection(self.HOST, self.PORT)
        self.connection.request(method, uri, body, headers)
        return self.connection.getresponse()


class BaseHTTPServerTestCase(BaseTestCase):
    class request_handler(NoLogRequestHandler, BaseHTTPRequestHandler):
        protocol_version = 'HTTP/1.1'
        default_request_version = 'HTTP/1.1'

        def do_TEST(self):
            self.send_response(204)
            self.send_header('Content-Type', 'text/html')
            self.send_header('Connection', 'close')
            self.end_headers()

        def do_KEEP(self):
            self.send_response(204)
            self.send_header('Content-Type', 'text/html')
            self.send_header('Connection', 'keep-alive')
            self.end_headers()

        def do_KEYERROR(self):
            self.send_error(999)

        def do_NOTFOUND(self):
            self.send_error(404)

        def do_EXPLAINERROR(self):
            self.send_error(999, "Short Message",
                            "This is a long \n explaination")

        def do_CUSTOM(self):
            self.send_response(999)
            self.send_header('Content-Type', 'text/html')
            self.send_header('Connection', 'close')
            self.end_headers()

        def do_LATINONEHEADER(self):
            self.send_response(999)
            self.send_header('X-Special', 'Dängerous Mind')
            self.send_header('Connection', 'close')
            self.end_headers()
            body = self.headers['x-special-incoming'].encode('utf-8')
            self.wfile.write(body)

    def setUp(self):
        BaseTestCase.setUp(self)
        self.con = http.client.HTTPConnection(self.HOST, self.PORT)
        self.con.connect()

    def test_command(self):
        self.con.request('GET', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 501)

    def test_request_line_trimming(self):
        self.con._http_vsn_str = 'HTTP/1.1\n'
        self.con.putrequest('GET', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 501)

    def test_version_bogus(self):
        self.con._http_vsn_str = 'FUBAR'
        self.con.putrequest('GET', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 400)

    def test_version_digits(self):
        self.con._http_vsn_str = 'HTTP/9.9.9'
        self.con.putrequest('GET', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 400)

    def test_version_none_get(self):
        self.con._http_vsn_str = ''
        self.con.putrequest('GET', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 501)

    def test_version_none(self):
        self.con._http_vsn_str = ''
        self.con.putrequest('PUT', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 400)

    def test_version_invalid(self):
        self.con._http_vsn = 99
        self.con._http_vsn_str = 'HTTP/9.9'
        self.con.putrequest('GET', '/')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 505)

    def test_send_blank(self):
        self.con._http_vsn_str = ''
        self.con.putrequest('', '')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 400)

    def test_header_close(self):
        self.con.putrequest('GET', '/')
        self.con.putheader('Connection', 'close')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 501)

    def test_head_keep_alive(self):
        self.con._http_vsn_str = 'HTTP/1.1'
        self.con.putrequest('GET', '/')
        self.con.putheader('Connection', 'keep-alive')
        self.con.endheaders()
        res = self.con.getresponse()
        self.assertEqual(res.status, 501)

    def test_handler(self):
        self.con.request('TEST', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 204)

    def test_return_header_keep_alive(self):
        self.con.request('KEEP', '/')
        res = self.con.getresponse()
        self.assertEqual(res.getheader('Connection'), 'keep-alive')
        self.con.request('TEST', '/')
        self.addCleanup(self.con.close)

    def test_internal_key_error(self):
        self.con.request('KEYERROR', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 999)

    def test_return_custom_status(self):
        self.con.request('CUSTOM', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 999)

    def test_return_explain_error(self):
        self.con.request('EXPLAINERROR', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 999)
        self.assertTrue(int(res.getheader('Content-Length')))

    def test_latin1_header(self):
        self.con.request('LATINONEHEADER', '/', headers={
            'X-Special-Incoming':       'Ärger mit Unicode'
        })
        res = self.con.getresponse()
        self.assertEqual(res.getheader('X-Special'), 'Dängerous Mind')
        self.assertEqual(res.read(), 'Ärger mit Unicode'.encode('utf-8'))

    def test_error_content_length(self):
        # Issue #16088: standard error responses should have a content-length
        self.con.request('NOTFOUND', '/')
        res = self.con.getresponse()
        self.assertEqual(res.status, 404)
        data = res.read()
        self.assertEqual(int(res.getheader('Content-Length')), len(data))


class SimpleHTTPServerTestCase(BaseTestCase):
    class request_handler(NoLogRequestHandler, SimpleHTTPRequestHandler):
        pass

    def setUp(self):
        BaseTestCase.setUp(self)
        self.cwd = os.getcwd()
        basetempdir = tempfile.gettempdir()
        os.chdir(basetempdir)
        self.data = b'We are the knights who say Ni!'
        self.tempdir = tempfile.mkdtemp(dir=basetempdir)
        self.tempdir_name = os.path.basename(self.tempdir)
        with open(os.path.join(self.tempdir, 'test'), 'wb') as temp:
            temp.write(self.data)

    def tearDown(self):
        try:
            os.chdir(self.cwd)
            try:
                shutil.rmtree(self.tempdir)
            except:
                pass
        finally:
            BaseTestCase.tearDown(self)

    def check_status_and_reason(self, response, status, data=None):
        body = response.read()
        self.assertTrue(response)
        self.assertEqual(response.status, status)
        self.assertIsNotNone(response.reason)
        if data:
            self.assertEqual(data, body)

    def test_get(self):
        #constructs the path relative to the root directory of the HTTPServer
        response = self.request(self.tempdir_name + '/test')
        self.check_status_and_reason(response, 200, data=self.data)
        # check for trailing "/" which should return 404. See Issue17324
        response = self.request(self.tempdir_name + '/test/')
        self.check_status_and_reason(response, 404)
        response = self.request(self.tempdir_name + '/')
        self.check_status_and_reason(response, 200)
        response = self.request(self.tempdir_name)
        self.check_status_and_reason(response, 301)
        response = self.request('/ThisDoesNotExist')
        self.check_status_and_reason(response, 404)
        response = self.request('/' + 'ThisDoesNotExist' + '/')
        self.check_status_and_reason(response, 404)
        with open(os.path.join(self.tempdir_name, 'index.html'), 'w') as f:
            response = self.request('/' + self.tempdir_name + '/')
            self.check_status_and_reason(response, 200)
            # chmod() doesn't work as expected on Windows, and filesystem
            # permissions are ignored by root on Unix.
            if os.name == 'posix' and os.geteuid() != 0:
                os.chmod(self.tempdir, 0)
                response = self.request(self.tempdir_name + '/')
                self.check_status_and_reason(response, 404)
                os.chmod(self.tempdir, 0o755)

    def test_head(self):
        response = self.request(
            self.tempdir_name + '/test', method='HEAD')
        self.check_status_and_reason(response, 200)
        self.assertEqual(response.getheader('content-length'),
                         str(len(self.data)))
        self.assertEqual(response.getheader('content-type'),
                         'application/octet-stream')

    def test_invalid_requests(self):
        response = self.request('/', method='FOO')
        self.check_status_and_reason(response, 501)
        # requests must be case sensitive,so this should fail too
        response = self.request('/', method='get')
        self.check_status_and_reason(response, 501)
        response = self.request('/', method='GETs')
        self.check_status_and_reason(response, 501)


cgi_file1 = """\
#!%s

print("Content-type: text/html")
print()
print("Hello World")
"""

cgi_file2 = """\
#!%s
import cgi

print("Content-type: text/html")
print()

form = cgi.FieldStorage()
print("%%s, %%s, %%s" %% (form.getfirst("spam"), form.getfirst("eggs"),
                          form.getfirst("bacon")))
"""


@unittest.skipIf(hasattr(os, 'geteuid') and os.geteuid() == 0,
        "This test can't be run reliably as root (issue #13308).")
class CGIHTTPServerTestCase(BaseTestCase):
    class request_handler(NoLogRequestHandler, CGIHTTPRequestHandler):
        pass

    linesep = os.linesep.encode('ascii')

    def setUp(self):
        BaseTestCase.setUp(self)
        self.cwd = os.getcwd()
        self.parent_dir = tempfile.mkdtemp()
        self.cgi_dir = os.path.join(self.parent_dir, 'cgi-bin')
        os.mkdir(self.cgi_dir)
        self.nocgi_path = None
        self.file1_path = None
        self.file2_path = None

        # The shebang line should be pure ASCII: use symlink if possible.
        # See issue #7668.
        if support.can_symlink():
            self.pythonexe = os.path.join(self.parent_dir, 'python')
            os.symlink(sys.executable, self.pythonexe)
        else:
            self.pythonexe = sys.executable

        try:
            # The python executable path is written as the first line of the
            # CGI Python script. The encoding cookie cannot be used, and so the
            # path should be encodable to the default script encoding (utf-8)
            self.pythonexe.encode('utf-8')
        except UnicodeEncodeError:
            self.tearDown()
            self.skipTest("Python executable path is not encodable to utf-8")

        self.nocgi_path = os.path.join(self.parent_dir, 'nocgi.py')
        with open(self.nocgi_path, 'w') as fp:
            fp.write(cgi_file1 % self.pythonexe)
        os.chmod(self.nocgi_path, 0o777)

        self.file1_path = os.path.join(self.cgi_dir, 'file1.py')
        with open(self.file1_path, 'w', encoding='utf-8') as file1:
            file1.write(cgi_file1 % self.pythonexe)
        os.chmod(self.file1_path, 0o777)

        self.file2_path = os.path.join(self.cgi_dir, 'file2.py')
        with open(self.file2_path, 'w', encoding='utf-8') as file2:
            file2.write(cgi_file2 % self.pythonexe)
        os.chmod(self.file2_path, 0o777)

        os.chdir(self.parent_dir)

    def tearDown(self):
        try:
            os.chdir(self.cwd)
            if self.pythonexe != sys.executable:
                os.remove(self.pythonexe)
            if self.nocgi_path:
                os.remove(self.nocgi_path)
            if self.file1_path:
                os.remove(self.file1_path)
            if self.file2_path:
                os.remove(self.file2_path)
            os.rmdir(self.cgi_dir)
            os.rmdir(self.parent_dir)
        finally:
            BaseTestCase.tearDown(self)

    def test_url_collapse_path(self):
        # verify tail is the last portion and head is the rest on proper urls
        test_vectors = {
            '': '//',
            '..': IndexError,
            '/.//..': IndexError,
            '/': '//',
            '//': '//',
            '/\\': '//\\',
            '/.//': '//',
            'cgi-bin/file1.py': '/cgi-bin/file1.py',
            '/cgi-bin/file1.py': '/cgi-bin/file1.py',
            'a': '//a',
            '/a': '//a',
            '//a': '//a',
            './a': '//a',
            './C:/': '/C:/',
            '/a/b': '/a/b',
            '/a/b/': '/a/b/',
            '/a/b/.': '/a/b/',
            '/a/b/c/..': '/a/b/',
            '/a/b/c/../d': '/a/b/d',
            '/a/b/c/../d/e/../f': '/a/b/d/f',
            '/a/b/c/../d/e/../../f': '/a/b/f',
            '/a/b/c/../d/e/.././././..//f': '/a/b/f',
            '../a/b/c/../d/e/.././././..//f': IndexError,
            '/a/b/c/../d/e/../../../f': '/a/f',
            '/a/b/c/../d/e/../../../../f': '//f',
            '/a/b/c/../d/e/../../../../../f': IndexError,
            '/a/b/c/../d/e/../../../../f/..': '//',
            '/a/b/c/../d/e/../../../../f/../.': '//',
        }
        for path, expected in test_vectors.items():
            if isinstance(expected, type) and issubclass(expected, Exception):
                self.assertRaises(expected,
                                  server._url_collapse_path, path)
            else:
                actual = server._url_collapse_path(path)
                self.assertEqual(expected, actual,
                                 msg='path = %r\nGot:    %r\nWanted: %r' %
                                 (path, actual, expected))

    def test_headers_and_content(self):
        res = self.request('/cgi-bin/file1.py')
        self.assertEqual((b'Hello World' + self.linesep, 'text/html', 200),
            (res.read(), res.getheader('Content-type'), res.status))

    def test_issue19435(self):
        res = self.request('///////////nocgi.py/../cgi-bin/nothere.sh')
        self.assertEqual(res.status, 404)

    def test_post(self):
        params = urllib.parse.urlencode(
            {'spam' : 1, 'eggs' : 'python', 'bacon' : 123456})
        headers = {'Content-type' : 'application/x-www-form-urlencoded'}
        res = self.request('/cgi-bin/file2.py', 'POST', params, headers)

        self.assertEqual(res.read(), b'1, python, 123456' + self.linesep)

    def test_invaliduri(self):
        res = self.request('/cgi-bin/invalid')
        res.read()
        self.assertEqual(res.status, 404)

    def test_authorization(self):
        headers = {b'Authorization' : b'Basic ' +
                   base64.b64encode(b'username:pass')}
        res = self.request('/cgi-bin/file1.py', 'GET', headers=headers)
        self.assertEqual((b'Hello World' + self.linesep, 'text/html', 200),
                (res.read(), res.getheader('Content-type'), res.status))

    def test_no_leading_slash(self):
        # http://bugs.python.org/issue2254
        res = self.request('cgi-bin/file1.py')
        self.assertEqual((b'Hello World' + self.linesep, 'text/html', 200),
             (res.read(), res.getheader('Content-type'), res.status))

    def test_os_environ_is_not_altered(self):
        signature = "Test CGI Server"
        os.environ['SERVER_SOFTWARE'] = signature
        res = self.request('/cgi-bin/file1.py')
        self.assertEqual((b'Hello World' + self.linesep, 'text/html', 200),
                (res.read(), res.getheader('Content-type'), res.status))
        self.assertEqual(os.environ['SERVER_SOFTWARE'], signature)


class SocketlessRequestHandler(SimpleHTTPRequestHandler):
    def __init__(self):
        self.get_called = False
        self.protocol_version = "HTTP/1.1"

    def do_GET(self):
        self.get_called = True
        self.send_response(200)
        self.send_header('Content-Type', 'text/html')
        self.end_headers()
        self.wfile.write(b'<html><body>Data</body></html>\r\n')

    def log_message(self, format, *args):
        pass

class RejectingSocketlessRequestHandler(SocketlessRequestHandler):
    def handle_expect_100(self):
        self.send_error(417)
        return False


class AuditableBytesIO:

    def __init__(self):
        self.datas = []

    def write(self, data):
        self.datas.append(data)

    def getData(self):
        return b''.join(self.datas)

    @property
    def numWrites(self):
        return len(self.datas)


class BaseHTTPRequestHandlerTestCase(unittest.TestCase):
    """Test the functionality of the BaseHTTPServer.

       Test the support for the Expect 100-continue header.
       """

    HTTPResponseMatch = re.compile(b'HTTP/1.[0-9]+ 200 OK')

    def setUp (self):
        self.handler = SocketlessRequestHandler()

    def send_typical_request(self, message):
        input = BytesIO(message)
        output = BytesIO()
        self.handler.rfile = input
        self.handler.wfile = output
        self.handler.handle_one_request()
        output.seek(0)
        return output.readlines()

    def verify_get_called(self):
        self.assertTrue(self.handler.get_called)

    def verify_expected_headers(self, headers):
        for fieldName in b'Server: ', b'Date: ', b'Content-Type: ':
            self.assertEqual(sum(h.startswith(fieldName) for h in headers), 1)

    def verify_http_server_response(self, response):
        match = self.HTTPResponseMatch.search(response)
        self.assertTrue(match is not None)

    def test_http_1_1(self):
        result = self.send_typical_request(b'GET / HTTP/1.1\r\n\r\n')
        self.verify_http_server_response(result[0])
        self.verify_expected_headers(result[1:-1])
        self.verify_get_called()
        self.assertEqual(result[-1], b'<html><body>Data</body></html>\r\n')

    def test_http_1_0(self):
        result = self.send_typical_request(b'GET / HTTP/1.0\r\n\r\n')
        self.verify_http_server_response(result[0])
        self.verify_expected_headers(result[1:-1])
        self.verify_get_called()
        self.assertEqual(result[-1], b'<html><body>Data</body></html>\r\n')

    def test_http_0_9(self):
        result = self.send_typical_request(b'GET / HTTP/0.9\r\n\r\n')
        self.assertEqual(len(result), 1)
        self.assertEqual(result[0], b'<html><body>Data</body></html>\r\n')
        self.verify_get_called()

    def test_with_continue_1_0(self):
        result = self.send_typical_request(b'GET / HTTP/1.0\r\nExpect: 100-continue\r\n\r\n')
        self.verify_http_server_response(result[0])
        self.verify_expected_headers(result[1:-1])
        self.verify_get_called()
        self.assertEqual(result[-1], b'<html><body>Data</body></html>\r\n')

    def test_with_continue_1_1(self):
        result = self.send_typical_request(b'GET / HTTP/1.1\r\nExpect: 100-continue\r\n\r\n')
        self.assertEqual(result[0], b'HTTP/1.1 100 Continue\r\n')
        self.assertEqual(result[1], b'\r\n')
        self.assertEqual(result[2], b'HTTP/1.1 200 OK\r\n')
        self.verify_expected_headers(result[2:-1])
        self.verify_get_called()
        self.assertEqual(result[-1], b'<html><body>Data</body></html>\r\n')

    def test_header_buffering_of_send_error(self):

        input = BytesIO(b'GET / HTTP/1.1\r\n\r\n')
        output = AuditableBytesIO()
        handler = SocketlessRequestHandler()
        handler.rfile = input
        handler.wfile = output
        handler.request_version = 'HTTP/1.1'
        handler.requestline = ''
        handler.command = None

        handler.send_error(418)
        self.assertEqual(output.numWrites, 2)

    def test_header_buffering_of_send_response_only(self):

        input = BytesIO(b'GET / HTTP/1.1\r\n\r\n')
        output = AuditableBytesIO()
        handler = SocketlessRequestHandler()
        handler.rfile = input
        handler.wfile = output
        handler.request_version = 'HTTP/1.1'

        handler.send_response_only(418)
        self.assertEqual(output.numWrites, 0)
        handler.end_headers()
        self.assertEqual(output.numWrites, 1)

    def test_header_buffering_of_send_header(self):

        input = BytesIO(b'GET / HTTP/1.1\r\n\r\n')
        output = AuditableBytesIO()
        handler = SocketlessRequestHandler()
        handler.rfile = input
        handler.wfile = output
        handler.request_version = 'HTTP/1.1'

        handler.send_header('Foo', 'foo')
        handler.send_header('bar', 'bar')
        self.assertEqual(output.numWrites, 0)
        handler.end_headers()
        self.assertEqual(output.getData(), b'Foo: foo\r\nbar: bar\r\n\r\n')
        self.assertEqual(output.numWrites, 1)

    def test_header_unbuffered_when_continue(self):

        def _readAndReseek(f):
            pos = f.tell()
            f.seek(0)
            data = f.read()
            f.seek(pos)
            return data

        input = BytesIO(b'GET / HTTP/1.1\r\nExpect: 100-continue\r\n\r\n')
        output = BytesIO()
        self.handler.rfile = input
        self.handler.wfile = output
        self.handler.request_version = 'HTTP/1.1'

        self.handler.handle_one_request()
        self.assertNotEqual(_readAndReseek(output), b'')
        result = _readAndReseek(output).split(b'\r\n')
        self.assertEqual(result[0], b'HTTP/1.1 100 Continue')
        self.assertEqual(result[1], b'')
        self.assertEqual(result[2], b'HTTP/1.1 200 OK')

    def test_with_continue_rejected(self):
        usual_handler = self.handler        # Save to avoid breaking any subsequent tests.
        self.handler = RejectingSocketlessRequestHandler()
        result = self.send_typical_request(b'GET / HTTP/1.1\r\nExpect: 100-continue\r\n\r\n')
        self.assertEqual(result[0], b'HTTP/1.1 417 Expectation Failed\r\n')
        self.verify_expected_headers(result[1:-1])
        # The expect handler should short circuit the usual get method by
        # returning false here, so get_called should be false
        self.assertFalse(self.handler.get_called)
        self.assertEqual(sum(r == b'Connection: close\r\n' for r in result[1:-1]), 1)
        self.handler = usual_handler        # Restore to avoid breaking any subsequent tests.

    def test_request_length(self):
        # Issue #10714: huge request lines are discarded, to avoid Denial
        # of Service attacks.
        result = self.send_typical_request(b'GET ' + b'x' * 65537)
        self.assertEqual(result[0], b'HTTP/1.1 414 Request-URI Too Long\r\n')
        self.assertFalse(self.handler.get_called)

    def test_header_length(self):
        # Issue #6791: same for headers
        result = self.send_typical_request(
            b'GET / HTTP/1.1\r\nX-Foo: bar' + b'r' * 65537 + b'\r\n\r\n')
        self.assertEqual(result[0], b'HTTP/1.1 400 Line too long\r\n')
        self.assertFalse(self.handler.get_called)

class SimpleHTTPRequestHandlerTestCase(unittest.TestCase):
    """ Test url parsing """
    def setUp(self):
        self.translated = os.getcwd()
        self.translated = os.path.join(self.translated, 'filename')
        self.handler = SocketlessRequestHandler()

    def test_query_arguments(self):
        path = self.handler.translate_path('/filename')
        self.assertEqual(path, self.translated)
        path = self.handler.translate_path('/filename?foo=bar')
        self.assertEqual(path, self.translated)
        path = self.handler.translate_path('/filename?a=b&spam=eggs#zot')
        self.assertEqual(path, self.translated)

    def test_start_with_double_slash(self):
        path = self.handler.translate_path('//filename')
        self.assertEqual(path, self.translated)
        path = self.handler.translate_path('//filename?foo=bar')
        self.assertEqual(path, self.translated)


def test_main(verbose=None):
    cwd = os.getcwd()
    try:
        support.run_unittest(
            BaseHTTPRequestHandlerTestCase,
            BaseHTTPServerTestCase,
            SimpleHTTPServerTestCase,
            CGIHTTPServerTestCase,
            SimpleHTTPRequestHandlerTestCase,
        )
    finally:
        os.chdir(cwd)

if __name__ == '__main__':
    test_main()