ORPA-pyOpenRPA/Resources/WPy64-3720/python-3.7.2.amd64/Lib/site-packages/tornado/test/websocket_test.py

import asyncio
import functools
import traceback
import unittest

from tornado.concurrent import Future
from tornado import gen
from tornado.httpclient import HTTPError, HTTPRequest
from tornado.locks import Event
from tornado.log import gen_log, app_log
from tornado.simple_httpclient import SimpleAsyncHTTPClient
from tornado.template import DictLoader
from tornado.testing import AsyncHTTPTestCase, gen_test, bind_unused_port, ExpectLog
from tornado.web import Application, RequestHandler

try:
    import tornado.websocket  # noqa: F401
    from tornado.util import _websocket_mask_python
except ImportError:
    # The unittest module presents misleading errors on ImportError
    # (it acts as if websocket_test could not be found, hiding the underlying
    # error).  If we get an ImportError here (which could happen due to
    # TORNADO_EXTENSION=1), print some extra information before failing.
    traceback.print_exc()
    raise

from tornado.websocket import (
    WebSocketHandler,
    websocket_connect,
    WebSocketError,
    WebSocketClosedError,
)

try:
    from tornado import speedups
except ImportError:
    speedups = None  # type: ignore


class TestWebSocketHandler(WebSocketHandler):
    """Base class for testing handlers that exposes the on_close event.

    This allows for tests to see the close code and reason on the
    server side.

    """

    def initialize(self, close_future=None, compression_options=None):
        self.close_future = close_future
        self.compression_options = compression_options

    def get_compression_options(self):
        return self.compression_options

    def on_close(self):
        if self.close_future is not None:
            self.close_future.set_result((self.close_code, self.close_reason))


class EchoHandler(TestWebSocketHandler):
    @gen.coroutine
    def on_message(self, message):
        try:
            yield self.write_message(message, isinstance(message, bytes))
        except asyncio.CancelledError:
            pass
        except WebSocketClosedError:
            pass


class ErrorInOnMessageHandler(TestWebSocketHandler):
    def on_message(self, message):
        1 / 0


class HeaderHandler(TestWebSocketHandler):
    def open(self):
        methods_to_test = [
            functools.partial(self.write, "This should not work"),
            functools.partial(self.redirect, "http://localhost/elsewhere"),
            functools.partial(self.set_header, "X-Test", ""),
            functools.partial(self.set_cookie, "Chocolate", "Chip"),
            functools.partial(self.set_status, 503),
            self.flush,
            self.finish,
        ]
        for method in methods_to_test:
            try:
                # In a websocket context, many RequestHandler methods
                # raise RuntimeErrors.
                method()
                raise Exception("did not get expected exception")
            except RuntimeError:
                pass
        self.write_message(self.request.headers.get("X-Test", ""))


class HeaderEchoHandler(TestWebSocketHandler):
    def set_default_headers(self):
        self.set_header("X-Extra-Response-Header", "Extra-Response-Value")

    def prepare(self):
        for k, v in self.request.headers.get_all():
            if k.lower().startswith("x-test"):
                self.set_header(k, v)


class NonWebSocketHandler(RequestHandler):
    def get(self):
        self.write("ok")


class CloseReasonHandler(TestWebSocketHandler):
    def open(self):
        self.on_close_called = False
        self.close(1001, "goodbye")


class AsyncPrepareHandler(TestWebSocketHandler):
    @gen.coroutine
    def prepare(self):
        yield gen.moment

    def on_message(self, message):
        self.write_message(message)


class PathArgsHandler(TestWebSocketHandler):
    def open(self, arg):
        self.write_message(arg)


class CoroutineOnMessageHandler(TestWebSocketHandler):
    def initialize(self, **kwargs):
        super(CoroutineOnMessageHandler, self).initialize(**kwargs)
        self.sleeping = 0

    @gen.coroutine
    def on_message(self, message):
        if self.sleeping > 0:
            self.write_message("another coroutine is already sleeping")
        self.sleeping += 1
        yield gen.sleep(0.01)
        self.sleeping -= 1
        self.write_message(message)


class RenderMessageHandler(TestWebSocketHandler):
    def on_message(self, message):
        self.write_message(self.render_string("message.html", message=message))


class SubprotocolHandler(TestWebSocketHandler):
    def initialize(self, **kwargs):
        super(SubprotocolHandler, self).initialize(**kwargs)
        self.select_subprotocol_called = False

    def select_subprotocol(self, subprotocols):
        if self.select_subprotocol_called:
            raise Exception("select_subprotocol called twice")
        self.select_subprotocol_called = True
        if "goodproto" in subprotocols:
            return "goodproto"
        return None

    def open(self):
        if not self.select_subprotocol_called:
            raise Exception("select_subprotocol not called")
        self.write_message("subprotocol=%s" % self.selected_subprotocol)


class OpenCoroutineHandler(TestWebSocketHandler):
    def initialize(self, test, **kwargs):
        super(OpenCoroutineHandler, self).initialize(**kwargs)
        self.test = test
        self.open_finished = False

    @gen.coroutine
    def open(self):
        yield self.test.message_sent.wait()
        yield gen.sleep(0.010)
        self.open_finished = True

    def on_message(self, message):
        if not self.open_finished:
            raise Exception("on_message called before open finished")
        self.write_message("ok")


class ErrorInOpenHandler(TestWebSocketHandler):
    def open(self):
        raise Exception("boom")


class ErrorInAsyncOpenHandler(TestWebSocketHandler):
    async def open(self):
        await asyncio.sleep(0)
        raise Exception("boom")


class NoDelayHandler(TestWebSocketHandler):
    def open(self):
        self.set_nodelay(True)
        self.write_message("hello")


class WebSocketBaseTestCase(AsyncHTTPTestCase):
    @gen.coroutine
    def ws_connect(self, path, **kwargs):
        ws = yield websocket_connect(
            "ws://127.0.0.1:%d%s" % (self.get_http_port(), path), **kwargs
        )
        raise gen.Return(ws)


class WebSocketTest(WebSocketBaseTestCase):
    def get_app(self):
        self.close_future = Future()  # type: Future[None]
        return Application(
            [
                ("/echo", EchoHandler, dict(close_future=self.close_future)),
                ("/non_ws", NonWebSocketHandler),
                ("/header", HeaderHandler, dict(close_future=self.close_future)),
                (
                    "/header_echo",
                    HeaderEchoHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/close_reason",
                    CloseReasonHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/error_in_on_message",
                    ErrorInOnMessageHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/async_prepare",
                    AsyncPrepareHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/path_args/(.*)",
                    PathArgsHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/coroutine",
                    CoroutineOnMessageHandler,
                    dict(close_future=self.close_future),
                ),
                ("/render", RenderMessageHandler, dict(close_future=self.close_future)),
                (
                    "/subprotocol",
                    SubprotocolHandler,
                    dict(close_future=self.close_future),
                ),
                (
                    "/open_coroutine",
                    OpenCoroutineHandler,
                    dict(close_future=self.close_future, test=self),
                ),
                ("/error_in_open", ErrorInOpenHandler),
                ("/error_in_async_open", ErrorInAsyncOpenHandler),
                ("/nodelay", NoDelayHandler),
            ],
            template_loader=DictLoader({"message.html": "<b>{{ message }}</b>"}),
        )

    def get_http_client(self):
        # These tests require HTTP/1; force the use of SimpleAsyncHTTPClient.
        return SimpleAsyncHTTPClient()

    def tearDown(self):
        super(WebSocketTest, self).tearDown()
        RequestHandler._template_loaders.clear()

    def test_http_request(self):
        # WS server, HTTP client.
        response = self.fetch("/echo")
        self.assertEqual(response.code, 400)

    def test_missing_websocket_key(self):
        response = self.fetch(
            "/echo",
            headers={
                "Connection": "Upgrade",
                "Upgrade": "WebSocket",
                "Sec-WebSocket-Version": "13",
            },
        )
        self.assertEqual(response.code, 400)

    def test_bad_websocket_version(self):
        response = self.fetch(
            "/echo",
            headers={
                "Connection": "Upgrade",
                "Upgrade": "WebSocket",
                "Sec-WebSocket-Version": "12",
            },
        )
        self.assertEqual(response.code, 426)

    @gen_test
    def test_websocket_gen(self):
        ws = yield self.ws_connect("/echo")
        yield ws.write_message("hello")
        response = yield ws.read_message()
        self.assertEqual(response, "hello")

    def test_websocket_callbacks(self):
        websocket_connect(
            "ws://127.0.0.1:%d/echo" % self.get_http_port(), callback=self.stop
        )
        ws = self.wait().result()
        ws.write_message("hello")
        ws.read_message(self.stop)
        response = self.wait().result()
        self.assertEqual(response, "hello")
        self.close_future.add_done_callback(lambda f: self.stop())
        ws.close()
        self.wait()

    @gen_test
    def test_binary_message(self):
        ws = yield self.ws_connect("/echo")
        ws.write_message(b"hello \xe9", binary=True)
        response = yield ws.read_message()
        self.assertEqual(response, b"hello \xe9")

    @gen_test
    def test_unicode_message(self):
        ws = yield self.ws_connect("/echo")
        ws.write_message(u"hello \u00e9")
        response = yield ws.read_message()
        self.assertEqual(response, u"hello \u00e9")

    @gen_test
    def test_render_message(self):
        ws = yield self.ws_connect("/render")
        ws.write_message("hello")
        response = yield ws.read_message()
        self.assertEqual(response, "<b>hello</b>")

    @gen_test
    def test_error_in_on_message(self):
        ws = yield self.ws_connect("/error_in_on_message")
        ws.write_message("hello")
        with ExpectLog(app_log, "Uncaught exception"):
            response = yield ws.read_message()
        self.assertIs(response, None)

    @gen_test
    def test_websocket_http_fail(self):
        with self.assertRaises(HTTPError) as cm:
            yield self.ws_connect("/notfound")
        self.assertEqual(cm.exception.code, 404)

    @gen_test
    def test_websocket_http_success(self):
        with self.assertRaises(WebSocketError):
            yield self.ws_connect("/non_ws")

    @gen_test
    def test_websocket_network_fail(self):
        sock, port = bind_unused_port()
        sock.close()
        with self.assertRaises(IOError):
            with ExpectLog(gen_log, ".*"):
                yield websocket_connect(
                    "ws://127.0.0.1:%d/" % port, connect_timeout=3600
                )

    @gen_test
    def test_websocket_close_buffered_data(self):
        ws = yield websocket_connect("ws://127.0.0.1:%d/echo" % self.get_http_port())
        ws.write_message("hello")
        ws.write_message("world")
        # Close the underlying stream.
        ws.stream.close()

    @gen_test
    def test_websocket_headers(self):
        # Ensure that arbitrary headers can be passed through websocket_connect.
        ws = yield websocket_connect(
            HTTPRequest(
                "ws://127.0.0.1:%d/header" % self.get_http_port(),
                headers={"X-Test": "hello"},
            )
        )
        response = yield ws.read_message()
        self.assertEqual(response, "hello")

    @gen_test
    def test_websocket_header_echo(self):
        # Ensure that headers can be returned in the response.
        # Specifically, that arbitrary headers passed through websocket_connect
        # can be returned.
        ws = yield websocket_connect(
            HTTPRequest(
                "ws://127.0.0.1:%d/header_echo" % self.get_http_port(),
                headers={"X-Test-Hello": "hello"},
            )
        )
        self.assertEqual(ws.headers.get("X-Test-Hello"), "hello")
        self.assertEqual(
            ws.headers.get("X-Extra-Response-Header"), "Extra-Response-Value"
        )

    @gen_test
    def test_server_close_reason(self):
        ws = yield self.ws_connect("/close_reason")
        msg = yield ws.read_message()
        # A message of None means the other side closed the connection.
        self.assertIs(msg, None)
        self.assertEqual(ws.close_code, 1001)
        self.assertEqual(ws.close_reason, "goodbye")
        # The on_close callback is called no matter which side closed.
        code, reason = yield self.close_future
        # The client echoed the close code it received to the server,
        # so the server's close code (returned via close_future) is
        # the same.
        self.assertEqual(code, 1001)

    @gen_test
    def test_client_close_reason(self):
        ws = yield self.ws_connect("/echo")
        ws.close(1001, "goodbye")
        code, reason = yield self.close_future
        self.assertEqual(code, 1001)
        self.assertEqual(reason, "goodbye")

    @gen_test
    def test_write_after_close(self):
        ws = yield self.ws_connect("/close_reason")
        msg = yield ws.read_message()
        self.assertIs(msg, None)
        with self.assertRaises(WebSocketClosedError):
            ws.write_message("hello")

    @gen_test
    def test_async_prepare(self):
        # Previously, an async prepare method triggered a bug that would
        # result in a timeout on test shutdown (and a memory leak).
        ws = yield self.ws_connect("/async_prepare")
        ws.write_message("hello")
        res = yield ws.read_message()
        self.assertEqual(res, "hello")

    @gen_test
    def test_path_args(self):
        ws = yield self.ws_connect("/path_args/hello")
        res = yield ws.read_message()
        self.assertEqual(res, "hello")

    @gen_test
    def test_coroutine(self):
        ws = yield self.ws_connect("/coroutine")
        # Send both messages immediately, coroutine must process one at a time.
        yield ws.write_message("hello1")
        yield ws.write_message("hello2")
        res = yield ws.read_message()
        self.assertEqual(res, "hello1")
        res = yield ws.read_message()
        self.assertEqual(res, "hello2")

    @gen_test
    def test_check_origin_valid_no_path(self):
        port = self.get_http_port()

        url = "ws://127.0.0.1:%d/echo" % port
        headers = {"Origin": "http://127.0.0.1:%d" % port}

        ws = yield websocket_connect(HTTPRequest(url, headers=headers))
        ws.write_message("hello")
        response = yield ws.read_message()
        self.assertEqual(response, "hello")

    @gen_test
    def test_check_origin_valid_with_path(self):
        port = self.get_http_port()

        url = "ws://127.0.0.1:%d/echo" % port
        headers = {"Origin": "http://127.0.0.1:%d/something" % port}

        ws = yield websocket_connect(HTTPRequest(url, headers=headers))
        ws.write_message("hello")
        response = yield ws.read_message()
        self.assertEqual(response, "hello")

    @gen_test
    def test_check_origin_invalid_partial_url(self):
        port = self.get_http_port()

        url = "ws://127.0.0.1:%d/echo" % port
        headers = {"Origin": "127.0.0.1:%d" % port}

        with self.assertRaises(HTTPError) as cm:
            yield websocket_connect(HTTPRequest(url, headers=headers))
        self.assertEqual(cm.exception.code, 403)

    @gen_test
    def test_check_origin_invalid(self):
        port = self.get_http_port()

        url = "ws://127.0.0.1:%d/echo" % port
        # Host is 127.0.0.1, which should not be accessible from some other
        # domain
        headers = {"Origin": "http://somewhereelse.com"}

        with self.assertRaises(HTTPError) as cm:
            yield websocket_connect(HTTPRequest(url, headers=headers))

        self.assertEqual(cm.exception.code, 403)

    @gen_test
    def test_check_origin_invalid_subdomains(self):
        port = self.get_http_port()

        url = "ws://localhost:%d/echo" % port
        # Subdomains should be disallowed by default.  If we could pass a
        # resolver to websocket_connect we could test sibling domains as well.
        headers = {"Origin": "http://subtenant.localhost"}

        with self.assertRaises(HTTPError) as cm:
            yield websocket_connect(HTTPRequest(url, headers=headers))

        self.assertEqual(cm.exception.code, 403)

    @gen_test
    def test_subprotocols(self):
        ws = yield self.ws_connect(
            "/subprotocol", subprotocols=["badproto", "goodproto"]
        )
        self.assertEqual(ws.selected_subprotocol, "goodproto")
        res = yield ws.read_message()
        self.assertEqual(res, "subprotocol=goodproto")

    @gen_test
    def test_subprotocols_not_offered(self):
        ws = yield self.ws_connect("/subprotocol")
        self.assertIs(ws.selected_subprotocol, None)
        res = yield ws.read_message()
        self.assertEqual(res, "subprotocol=None")

    @gen_test
    def test_open_coroutine(self):
        self.message_sent = Event()
        ws = yield self.ws_connect("/open_coroutine")
        yield ws.write_message("hello")
        self.message_sent.set()
        res = yield ws.read_message()
        self.assertEqual(res, "ok")

    @gen_test
    def test_error_in_open(self):
        with ExpectLog(app_log, "Uncaught exception"):
            ws = yield self.ws_connect("/error_in_open")
            res = yield ws.read_message()
        self.assertIsNone(res)

    @gen_test
    def test_error_in_async_open(self):
        with ExpectLog(app_log, "Uncaught exception"):
            ws = yield self.ws_connect("/error_in_async_open")
            res = yield ws.read_message()
        self.assertIsNone(res)

    @gen_test
    def test_nodelay(self):
        ws = yield self.ws_connect("/nodelay")
        res = yield ws.read_message()
        self.assertEqual(res, "hello")


class NativeCoroutineOnMessageHandler(TestWebSocketHandler):
    def initialize(self, **kwargs):
        super().initialize(**kwargs)
        self.sleeping = 0

    async def on_message(self, message):
        if self.sleeping > 0:
            self.write_message("another coroutine is already sleeping")
        self.sleeping += 1
        await gen.sleep(0.01)
        self.sleeping -= 1
        self.write_message(message)


class WebSocketNativeCoroutineTest(WebSocketBaseTestCase):
    def get_app(self):
        return Application([("/native", NativeCoroutineOnMessageHandler)])

    @gen_test
    def test_native_coroutine(self):
        ws = yield self.ws_connect("/native")
        # Send both messages immediately, coroutine must process one at a time.
        yield ws.write_message("hello1")
        yield ws.write_message("hello2")
        res = yield ws.read_message()
        self.assertEqual(res, "hello1")
        res = yield ws.read_message()
        self.assertEqual(res, "hello2")


class CompressionTestMixin(object):
    MESSAGE = "Hello world. Testing 123 123"

    def get_app(self):
        class LimitedHandler(TestWebSocketHandler):
            @property
            def max_message_size(self):
                return 1024

            def on_message(self, message):
                self.write_message(str(len(message)))

        return Application(
            [
                (
                    "/echo",
                    EchoHandler,
                    dict(compression_options=self.get_server_compression_options()),
                ),
                (
                    "/limited",
                    LimitedHandler,
                    dict(compression_options=self.get_server_compression_options()),
                ),
            ]
        )

    def get_server_compression_options(self):
        return None

    def get_client_compression_options(self):
        return None

    @gen_test
    def test_message_sizes(self):
        ws = yield self.ws_connect(
            "/echo", compression_options=self.get_client_compression_options()
        )
        # Send the same message three times so we can measure the
        # effect of the context_takeover options.
        for i in range(3):
            ws.write_message(self.MESSAGE)
            response = yield ws.read_message()
            self.assertEqual(response, self.MESSAGE)
        self.assertEqual(ws.protocol._message_bytes_out, len(self.MESSAGE) * 3)
        self.assertEqual(ws.protocol._message_bytes_in, len(self.MESSAGE) * 3)
        self.verify_wire_bytes(ws.protocol._wire_bytes_in, ws.protocol._wire_bytes_out)

    @gen_test
    def test_size_limit(self):
        ws = yield self.ws_connect(
            "/limited", compression_options=self.get_client_compression_options()
        )
        # Small messages pass through.
        ws.write_message("a" * 128)
        response = yield ws.read_message()
        self.assertEqual(response, "128")
        # This message is too big after decompression, but it compresses
        # down to a size that will pass the initial checks.
        ws.write_message("a" * 2048)
        response = yield ws.read_message()
        self.assertIsNone(response)


class UncompressedTestMixin(CompressionTestMixin):
    """Specialization of CompressionTestMixin when we expect no compression."""

    def verify_wire_bytes(self, bytes_in, bytes_out):
        # Bytes out includes the 4-byte mask key per message.
        self.assertEqual(bytes_out, 3 * (len(self.MESSAGE) + 6))
        self.assertEqual(bytes_in, 3 * (len(self.MESSAGE) + 2))


class NoCompressionTest(UncompressedTestMixin, WebSocketBaseTestCase):
    pass


# If only one side tries to compress, the extension is not negotiated.
class ServerOnlyCompressionTest(UncompressedTestMixin, WebSocketBaseTestCase):
    def get_server_compression_options(self):
        return {}


class ClientOnlyCompressionTest(UncompressedTestMixin, WebSocketBaseTestCase):
    def get_client_compression_options(self):
        return {}


class DefaultCompressionTest(CompressionTestMixin, WebSocketBaseTestCase):
    def get_server_compression_options(self):
        return {}

    def get_client_compression_options(self):
        return {}

    def verify_wire_bytes(self, bytes_in, bytes_out):
        self.assertLess(bytes_out, 3 * (len(self.MESSAGE) + 6))
        self.assertLess(bytes_in, 3 * (len(self.MESSAGE) + 2))
        # Bytes out includes the 4 bytes mask key per message.
        self.assertEqual(bytes_out, bytes_in + 12)


class MaskFunctionMixin(object):
    # Subclasses should define self.mask(mask, data)
    def test_mask(self):
        self.assertEqual(self.mask(b"abcd", b""), b"")
        self.assertEqual(self.mask(b"abcd", b"b"), b"\x03")
        self.assertEqual(self.mask(b"abcd", b"54321"), b"TVPVP")
        self.assertEqual(self.mask(b"ZXCV", b"98765432"), b"c`t`olpd")
        # Include test cases with \x00 bytes (to ensure that the C
        # extension isn't depending on null-terminated strings) and
        # bytes with the high bit set (to smoke out signedness issues).
        self.assertEqual(
            self.mask(b"\x00\x01\x02\x03", b"\xff\xfb\xfd\xfc\xfe\xfa"),
            b"\xff\xfa\xff\xff\xfe\xfb",
        )
        self.assertEqual(
            self.mask(b"\xff\xfb\xfd\xfc", b"\x00\x01\x02\x03\x04\x05"),
            b"\xff\xfa\xff\xff\xfb\xfe",
        )


class PythonMaskFunctionTest(MaskFunctionMixin, unittest.TestCase):
    def mask(self, mask, data):
        return _websocket_mask_python(mask, data)


@unittest.skipIf(speedups is None, "tornado.speedups module not present")
class CythonMaskFunctionTest(MaskFunctionMixin, unittest.TestCase):
    def mask(self, mask, data):
        return speedups.websocket_mask(mask, data)


class ServerPeriodicPingTest(WebSocketBaseTestCase):
    def get_app(self):
        class PingHandler(TestWebSocketHandler):
            def on_pong(self, data):
                self.write_message("got pong")

        return Application([("/", PingHandler)], websocket_ping_interval=0.01)

    @gen_test
    def test_server_ping(self):
        ws = yield self.ws_connect("/")
        for i in range(3):
            response = yield ws.read_message()
            self.assertEqual(response, "got pong")
        # TODO: test that the connection gets closed if ping responses stop.


class ClientPeriodicPingTest(WebSocketBaseTestCase):
    def get_app(self):
        class PingHandler(TestWebSocketHandler):
            def on_ping(self, data):
                self.write_message("got ping")

        return Application([("/", PingHandler)])

    @gen_test
    def test_client_ping(self):
        ws = yield self.ws_connect("/", ping_interval=0.01)
        for i in range(3):
            response = yield ws.read_message()
            self.assertEqual(response, "got ping")
        # TODO: test that the connection gets closed if ping responses stop.


class ManualPingTest(WebSocketBaseTestCase):
    def get_app(self):
        class PingHandler(TestWebSocketHandler):
            def on_ping(self, data):
                self.write_message(data, binary=isinstance(data, bytes))

        return Application([("/", PingHandler)])

    @gen_test
    def test_manual_ping(self):
        ws = yield self.ws_connect("/")

        self.assertRaises(ValueError, ws.ping, "a" * 126)

        ws.ping("hello")
        resp = yield ws.read_message()
        # on_ping always sees bytes.
        self.assertEqual(resp, b"hello")

        ws.ping(b"binary hello")
        resp = yield ws.read_message()
        self.assertEqual(resp, b"binary hello")


class MaxMessageSizeTest(WebSocketBaseTestCase):
    def get_app(self):
        return Application([("/", EchoHandler)], websocket_max_message_size=1024)

    @gen_test
    def test_large_message(self):
        ws = yield self.ws_connect("/")

        # Write a message that is allowed.
        msg = "a" * 1024
        ws.write_message(msg)
        resp = yield ws.read_message()
        self.assertEqual(resp, msg)

        # Write a message that is too large.
        ws.write_message(msg + "b")
        resp = yield ws.read_message()
        # A message of None means the other side closed the connection.
        self.assertIs(resp, None)
        self.assertEqual(ws.close_code, 1009)
        self.assertEqual(ws.close_reason, "message too big")
        # TODO: Needs tests of messages split over multiple
        # continuation frames.