1.7.1

For Tornado AsyncHTTPClient, replace the methods instead of the class.

README.rst

@@ -50,6 +50,7 @@ The following http libraries are supported:
 -  requests (both 1.x and 2.x versions)
 -  httplib2
 -  boto
+-  Tornado's AsyncHTTPClient
 
 Usage
 -----
@@ -108,10 +109,10 @@ If you don't like VCR's defaults, you can set options by instantiating a
     import vcr
 
     my_vcr = vcr.VCR(
-        serializer = 'json',
+        serializer='json',
-        cassette_library_dir = 'fixtures/cassettes',
+        cassette_library_dir='fixtures/cassettes',
-        record_mode = 'once',
+        record_mode='once',
-        match_on = ['uri', 'method'],
+        match_on=['uri', 'method'],
     )
 
     with my_vcr.use_cassette('test.json'):
@@ -416,12 +417,13 @@ that of ``before_record``:
 .. code:: python
 
     def scrub_string(string, replacement=''):
-        def before_record_reponse(response):
+        def before_record_response(response):
-            return response['body']['string'] = response['body']['string'].replace(string, replacement)
+            response['body']['string'] = response['body']['string'].replace(string, replacement)
-        return scrub_string
+            return response
+        return before_record_response
 
     my_vcr = vcr.VCR(
-        before_record=scrub_string(settings.USERNAME, 'username'),
+        before_record_response=scrub_string(settings.USERNAME, 'username'),
     )
     with my_vcr.use_cassette('test.yml'):
          # your http code here    
@@ -606,6 +608,12 @@ new API in version 1.0.x
 
 Changelog
 ---------
+-  1.7.1 [#183] Patch ``fetch_impl`` instead of the entire HTTPClient
+   class for Tornado (thanks @abhinav).
+-  1.7.0 [#177] Properly support coroutine/generator decoration. [#178]
+   Support distribute (thanks @graingert). [#163] Make compatibility
+   between python2 and python3 recorded cassettes more robust (thanks
+   @gward).
 -  1.6.1 [#169] Support conditional requirements in old versions of
    pip, Fix RST parse errors generated by pandoc, [Tornado] Fix
    unsupported features exception not being raised, [#166]

setup.py

@@ -1,12 +1,15 @@
 #!/usr/bin/env python
 
 import sys
+import logging
+
 from setuptools import setup, find_packages
 from setuptools.command.test import test as TestCommand
 import pkg_resources
 
 long_description = open('README.rst', 'r').read()
 
+
 class PyTest(TestCommand):
 
     def finalize_options(self):
@@ -21,7 +24,7 @@ class PyTest(TestCommand):
         sys.exit(errno)
 
 
-install_requires=['PyYAML', 'wrapt', 'six>=1.5']
+install_requires = ['PyYAML', 'wrapt', 'six>=1.5']
 
 
 extras_require = {
@@ -31,14 +34,24 @@ extras_require = {
 }
 
 
-if 'bdist_wheel' not in sys.argv:
+try:
+    if 'bdist_wheel' not in sys.argv:
+        for key, value in extras_require.items():
+            if key.startswith(':') and pkg_resources.evaluate_marker(key[1:]):
+                install_requires.extend(value)
+except Exception:
+    logging.getLogger(__name__).exception(
+        'Something went wrong calculating platform specific dependencies, so '
+        "you're getting them all!"
+    )
     for key, value in extras_require.items():
-        if key.startswith(':') and pkg_resources.evaluate_marker(key[1:]):
+        if key.startswith(':'):
             install_requires.extend(value)
 
+
 setup(
     name='vcrpy',
-    version='1.6.1',
+    version='1.7.1',
     description=(
         "Automatically mock your HTTP interactions to simplify and "
         "speed up testing"

tests/integration/test_tornado.py

@@ -275,3 +275,54 @@ def test_cannot_overwrite_cassette_raise_error_disabled(get_client, tmpdir):
         )
 
     assert isinstance(response.error, CannotOverwriteExistingCassetteException)
+
+
+@pytest.mark.gen_test
+@vcr.use_cassette(path_transformer=vcr.default_vcr.ensure_suffix('.yaml'))
+def test_tornado_with_decorator_use_cassette(get_client):
+    response = yield get_client().fetch(
+        http.HTTPRequest('http://www.google.com/', method='GET')
+    )
+    assert response.body.decode('utf-8') == "not actually google"
+
+
+@pytest.mark.gen_test
+@vcr.use_cassette(path_transformer=vcr.default_vcr.ensure_suffix('.yaml'))
+def test_tornado_exception_can_be_caught(get_client):
+    try:
+        yield get(get_client(), 'http://httpbin.org/status/500')
+    except http.HTTPError as e:
+        assert e.code == 500
+
+    try:
+        yield get(get_client(), 'http://httpbin.org/status/404')
+    except http.HTTPError as e:
+        assert e.code == 404
+
+
+@pytest.mark.gen_test
+def test_existing_references_get_patched(tmpdir):
+    from tornado.httpclient import AsyncHTTPClient
+
+    with vcr.use_cassette(str(tmpdir.join('data.yaml'))):
+        client = AsyncHTTPClient()
+        yield get(client, 'http://httpbin.org/get')
+
+    with vcr.use_cassette(str(tmpdir.join('data.yaml'))) as cass:
+        yield get(client, 'http://httpbin.org/get')
+        assert cass.play_count == 1
+
+
+@pytest.mark.gen_test
+def test_existing_instances_get_patched(get_client, tmpdir):
+    '''Ensure that existing instances of AsyncHTTPClient get patched upon
+    entering VCR context.'''
+
+    client = get_client()
+
+    with vcr.use_cassette(str(tmpdir.join('data.yaml'))):
+        yield get(client, 'http://httpbin.org/get')
+
+    with vcr.use_cassette(str(tmpdir.join('data.yaml'))) as cass:
+        yield get(client, 'http://httpbin.org/get')
+        assert cass.play_count == 1

tests/integration/test_tornado_exception_can_be_caught.yaml

@@ -0,0 +1,62 @@
+interactions:
+- request:
+    body: null
+    headers: {}
+    method: GET
+    uri: http://httpbin.org/status/500
+  response:
+    body: {string: !!python/unicode ''}
+    headers:
+    - !!python/tuple
+      - Content-Length
+      - ['0']
+    - !!python/tuple
+      - Server
+      - [nginx]
+    - !!python/tuple
+      - Connection
+      - [close]
+    - !!python/tuple
+      - Access-Control-Allow-Credentials
+      - ['true']
+    - !!python/tuple
+      - Date
+      - ['Thu, 30 Jul 2015 17:32:39 GMT']
+    - !!python/tuple
+      - Access-Control-Allow-Origin
+      - ['*']
+    - !!python/tuple
+      - Content-Type
+      - [text/html; charset=utf-8]
+    status: {code: 500, message: INTERNAL SERVER ERROR}
+- request:
+    body: null
+    headers: {}
+    method: GET
+    uri: http://httpbin.org/status/404
+  response:
+    body: {string: !!python/unicode ''}
+    headers:
+    - !!python/tuple
+      - Content-Length
+      - ['0']
+    - !!python/tuple
+      - Server
+      - [nginx]
+    - !!python/tuple
+      - Connection
+      - [close]
+    - !!python/tuple
+      - Access-Control-Allow-Credentials
+      - ['true']
+    - !!python/tuple
+      - Date
+      - ['Thu, 30 Jul 2015 17:32:39 GMT']
+    - !!python/tuple
+      - Access-Control-Allow-Origin
+      - ['*']
+    - !!python/tuple
+      - Content-Type
+      - [text/html; charset=utf-8]
+    status: {code: 404, message: NOT FOUND}
+version: 1

tests/integration/test_tornado_with_decorator_use_cassette.yaml

@@ -0,0 +1,53 @@
+interactions:
+- request:
+    body: null
+    headers: {}
+    method: GET
+    uri: http://www.google.com/
+  response:
+    body: {string: !!python/unicode 'not actually google'}
+    headers:
+    - !!python/tuple
+      - Expires
+      - ['-1']
+    - !!python/tuple
+      - Connection
+      - [close]
+    - !!python/tuple
+      - P3p
+      - ['CP="This is not a P3P policy! See http://www.google.com/support/accounts/bin/answer.py?hl=en&answer=151657
+          for more info."']
+    - !!python/tuple
+      - Alternate-Protocol
+      - ['80:quic,p=0']
+    - !!python/tuple
+      - Accept-Ranges
+      - [none]
+    - !!python/tuple
+      - X-Xss-Protection
+      - [1; mode=block]
+    - !!python/tuple
+      - Vary
+      - [Accept-Encoding]
+    - !!python/tuple
+      - Date
+      - ['Thu, 30 Jul 2015 08:41:40 GMT']
+    - !!python/tuple
+      - Cache-Control
+      - ['private, max-age=0']
+    - !!python/tuple
+      - Content-Type
+      - [text/html; charset=ISO-8859-1]
+    - !!python/tuple
+      - Set-Cookie
+      - ['PREF=ID=1111111111111111:FF=0:TM=1438245700:LM=1438245700:V=1:S=GAzVO0ALebSpC_cJ;
+          expires=Sat, 29-Jul-2017 08:41:40 GMT; path=/; domain=.google.com', 'NID=69=Br7oRAwgmKoK__HC6FEnuxglTFDmFxqP6Md63lKhzW1w6WkDbp3U90CDxnUKvDP6wJH8yxY5Lk5ZnFf66Q1B0d4OsYoKgq0vjfBAYXuCIAWtOuGZEOsFXanXs7pt2Mjx;
+          expires=Fri, 29-Jan-2016 08:41:40 GMT; path=/; domain=.google.com; HttpOnly']
+    - !!python/tuple
+      - X-Frame-Options
+      - [SAMEORIGIN]
+    - !!python/tuple
+      - Server
+      - [gws]
+    status: {code: 200, message: OK}
+version: 1

tests/unit/test_cassettes.py

@@ -253,3 +253,37 @@ def test_func_path_generator():
     def function_name(cassette):
         assert cassette._path == os.path.join(os.path.dirname(__file__), 'function_name')
     function_name()
+
+
+def test_use_as_decorator_on_coroutine():
+    original_http_connetion = httplib.HTTPConnection
+    @Cassette.use(inject=True)
+    def test_function(cassette):
+        assert httplib.HTTPConnection.cassette is cassette
+        assert httplib.HTTPConnection is not original_http_connetion
+        value = yield 1
+        assert value == 1
+        assert httplib.HTTPConnection.cassette is cassette
+        assert httplib.HTTPConnection is not original_http_connetion
+        value = yield 2
+        assert value == 2
+    coroutine = test_function()
+    value = next(coroutine)
+    while True:
+        try:
+            value = coroutine.send(value)
+        except StopIteration:
+            break
+
+
+def test_use_as_decorator_on_generator():
+    original_http_connetion = httplib.HTTPConnection
+    @Cassette.use(inject=True)
+    def test_function(cassette):
+        assert httplib.HTTPConnection.cassette is cassette
+        assert httplib.HTTPConnection is not original_http_connetion
+        yield 1
+        assert httplib.HTTPConnection.cassette is cassette
+        assert httplib.HTTPConnection is not original_http_connetion
+        yield 2
+    assert list(test_function()) == [1, 2]

tests/unit/test_serialize.py

@@ -1,3 +1,4 @@
+# -*- encoding: utf-8 -*-
 import pytest
 
 from vcr.compat import mock
@@ -27,6 +28,55 @@ def test_deserialize_new_json_cassette():
         deserialize(f.read(), jsonserializer)
 
 
+REQBODY_TEMPLATE = u'''\
+interactions:
+- request:
+    body: {req_body}
+    headers:
+      Content-Type: [application/x-www-form-urlencoded]
+      Host: [httpbin.org]
+    method: POST
+    uri: http://httpbin.org/post
+  response:
+    body: {{string: ""}}
+    headers:
+      content-length: ['0']
+      content-type: [application/json]
+    status: {{code: 200, message: OK}}
+'''
+
+
+# A cassette generated under Python 2 stores the request body as a string,
+# but the same cassette generated under Python 3 stores it as "!!binary".
+# Make sure we accept both forms, regardless of whether we're running under
+# Python 2 or 3.
+@pytest.mark.parametrize("req_body, expect", [
+    # Cassette written under Python 2 (pure ASCII body)
+    ('x=5&y=2', b'x=5&y=2'),
+    # Cassette written under Python 3 (pure ASCII body)
+    ('!!binary |\n      eD01Jnk9Mg==', b'x=5&y=2'),
+
+    # Request body has non-ASCII chars (x=föo&y=2), encoded in UTF-8.
+    ('!!python/str "x=f\\xF6o&y=2"', b'x=f\xc3\xb6o&y=2'),
+    ('!!binary |\n      eD1mw7ZvJnk9Mg==', b'x=f\xc3\xb6o&y=2'),
+
+    # Same request body, this time encoded in UTF-16. In this case, we
+    # write the same YAML file under both Python 2 and 3, so there's only
+    # one test case here.
+    ('!!binary |\n      //54AD0AZgD2AG8AJgB5AD0AMgA=',
+     b'\xff\xfex\x00=\x00f\x00\xf6\x00o\x00&\x00y\x00=\x002\x00'),
+
+    # Same again, this time encoded in ISO-8859-1.
+    ('!!binary |\n      eD1m9m8meT0y', b'x=f\xf6o&y=2'),
+])
+def test_deserialize_py2py3_yaml_cassette(tmpdir, req_body, expect):
+    cfile = tmpdir.join('test_cassette.yaml')
+    cfile.write(REQBODY_TEMPLATE.format(req_body=req_body))
+    with open(str(cfile)) as f:
+        (requests, responses) = deserialize(f.read(), yamlserializer)
+    assert requests[0].body == expect
+
+
 @mock.patch.object(jsonserializer.json, 'dumps',
                    side_effect=UnicodeDecodeError('utf-8', b'unicode error in serialization',
                                                   0, 10, 'blew up'))

vcr/cassette.py

@@ -1,11 +1,9 @@
-"""The container for recorded requests and responses"""
+import sys
-import functools
+import inspect
 import logging
 
-
 import wrapt
 
-# Internal imports
 from .compat import contextlib, collections
 from .errors import UnhandledHTTPRequestError
 from .matchers import requests_match, uri, method
@@ -50,14 +48,6 @@ class CassetteContextDecorator(object):
             # somewhere else.
             cassette._save()
 
-    @classmethod
-    def key_predicate(cls, key, value):
-        return key in cls._non_cassette_arguments
-
-    @classmethod
-    def _split_keys(cls, kwargs):
-        return partition_dict(cls.key_predicate, kwargs)
-
     def __enter__(self):
         # This assertion is here to prevent the dangerous behavior
         # that would result from forgetting about a __finish before
@@ -68,7 +58,10 @@ class CassetteContextDecorator(object):
         #     with context_decorator:
         #         pass
         assert self.__finish is None, "Cassette already open."
-        other_kwargs, cassette_kwargs = self._split_keys(self._args_getter())
+        other_kwargs, cassette_kwargs = partition_dict(
+            lambda key, _: key in self._non_cassette_arguments,
+            self._args_getter()
+        )
         if 'path_transformer' in other_kwargs:
             transformer = other_kwargs['path_transformer']
             cassette_kwargs['path'] = transformer(cassette_kwargs['path'])
@@ -84,27 +77,53 @@ class CassetteContextDecorator(object):
         # This awkward cloning thing is done to ensure that decorated
         # functions are reentrant. This is required for thread
         # safety and the correct operation of recursive functions.
-        args_getter = self._build_args_getter_for_decorator(
+        args_getter = self._build_args_getter_for_decorator(function)
-            function, self._args_getter
+        return type(self)(self.cls, args_getter)._execute_function(function, args, kwargs)
-        )
+
-        clone = type(self)(self.cls, args_getter)
+    def _execute_function(self, function, args, kwargs):
-        with clone as cassette:
+        if inspect.isgeneratorfunction(function):
-            if cassette.inject:
+            handler = self._handle_coroutine
-                return function(cassette, *args, **kwargs)
+        else:
-            else:
+            handler = self._handle_function
-                return function(*args, **kwargs)
+        return handler(function, args, kwargs)
+
+    def _handle_coroutine(self, function, args, kwargs):
+        """Wraps a coroutine so that we're inside the cassette context for the
+        duration of the coroutine.
+        """
+        with self as cassette:
+            coroutine = self.__handle_function(cassette, function, args, kwargs)
+            # We don't need to catch StopIteration. The caller (Tornado's
+            # gen.coroutine, for example) will handle that.
+            to_yield = next(coroutine)
+            while True:
+                try:
+                    to_send = yield to_yield
+                except Exception:
+                    to_yield = coroutine.throw(*sys.exc_info())
+                else:
+                    to_yield = coroutine.send(to_send)
+
+    def __handle_function(self, cassette, function, args, kwargs):
+        if cassette.inject:
+            return function(cassette, *args, **kwargs)
+        else:
+            return function(*args, **kwargs)
+
+    def _handle_function(self, function, args, kwargs):
+        with self as cassette:
+            self.__handle_function(cassette, function, args, kwargs)
 
     @staticmethod
     def get_function_name(function):
         return function.__name__
 
-    @classmethod
+    def _build_args_getter_for_decorator(self, function):
-    def _build_args_getter_for_decorator(cls, function, args_getter):
         def new_args_getter():
-            kwargs = args_getter()
+            kwargs = self._args_getter()
             if 'path' not in kwargs:
                 name_generator = (kwargs.get('func_path_generator') or
-                                  cls.get_function_name)
+                                  self.get_function_name)
                 path = name_generator(function)
                 kwargs['path'] = path
             return kwargs

vcr/config.py

@@ -107,7 +107,7 @@ class VCR(object):
         matcher_names = kwargs.get('match_on', self.match_on)
         path_transformer = kwargs.get(
             'path_transformer',
-            self.path_transformer
+            self.path_transformer or self.ensure_suffix('.yaml')
         )
         func_path_generator = kwargs.get(
             'func_path_generator',

vcr/matchers.py

@@ -43,11 +43,18 @@ def _header_checker(value, header='Content-Type'):
     return checker
 
 
+def _transform_json(body):
+    # Request body is always a byte string, but json.loads() wants a text
+    # string. RFC 7159 says the default encoding is UTF-8 (although UTF-16
+    # and UTF-32 are also allowed: hmmmmm).
+    return json.loads(body.decode('utf-8'))
+
+
 _xml_header_checker = _header_checker('text/xml')
 _xmlrpc_header_checker = _header_checker('xmlrpc', header='User-Agent')
 _checker_transformer_pairs = (
     (_header_checker('application/x-www-form-urlencoded'), urllib.parse.parse_qs),
-    (_header_checker('application/json'), json.loads),
+    (_header_checker('application/json'), _transform_json),
     (lambda request: _xml_header_checker(request) and _xmlrpc_header_checker(request), xmlrpc_client.loads),
 )
 

vcr/patch.py

@@ -54,13 +54,12 @@ else:
 
 # Try to save the original types for Tornado
 try:
-    import tornado.httpclient
     import tornado.simple_httpclient
 except ImportError:  # pragma: no cover
     pass
 else:
-    _AsyncHTTPClient = tornado.httpclient.AsyncHTTPClient
+    _SimpleAsyncHTTPClient_fetch_impl = \
-    _SimpleAsyncHTTPClient = tornado.simple_httpclient.SimpleAsyncHTTPClient
+            tornado.simple_httpclient.SimpleAsyncHTTPClient.fetch_impl
 
 
 try:
@@ -68,7 +67,8 @@ try:
 except ImportError:  # pragma: no cover
     pass
 else:
-    _CurlAsyncHTTPClient = tornado.curl_httpclient.CurlAsyncHTTPClient
+    _CurlAsyncHTTPClient_fetch_impl = \
+            tornado.curl_httpclient.CurlAsyncHTTPClient.fetch_impl
 
 
 class CassettePatcherBuilder(object):
@@ -228,23 +228,27 @@ class CassettePatcherBuilder(object):
     @_build_patchers_from_mock_triples_decorator
     def _tornado(self):
         try:
-            import tornado.httpclient as http
             import tornado.simple_httpclient as simple
         except ImportError:  # pragma: no cover
             pass
         else:
-            from .stubs.tornado_stubs import VCRAsyncHTTPClient
+            from .stubs.tornado_stubs import vcr_fetch_impl
-            from .stubs.tornado_stubs import VCRSimpleAsyncHTTPClient
 
-            yield http, 'AsyncHTTPClient', VCRAsyncHTTPClient
+            new_fetch_impl = vcr_fetch_impl(
-            yield simple, 'SimpleAsyncHTTPClient', VCRSimpleAsyncHTTPClient
+                self._cassette, _SimpleAsyncHTTPClient_fetch_impl
+            )
+            yield simple.SimpleAsyncHTTPClient, 'fetch_impl', new_fetch_impl
         try:
             import tornado.curl_httpclient as curl
         except ImportError:  # pragma: no cover
             pass
         else:
-            from .stubs.tornado_stubs import VCRCurlAsyncHTTPClient
+            from .stubs.tornado_stubs import vcr_fetch_impl
-            yield curl, 'CurlAsyncHTTPClient', VCRCurlAsyncHTTPClient
+
+            new_fetch_impl = vcr_fetch_impl(
+                self._cassette, _CurlAsyncHTTPClient_fetch_impl
+            )
+            yield curl.CurlAsyncHTTPClient, 'fetch_impl', new_fetch_impl
 
     def _urllib3_patchers(self, cpool, stubs):
         http_connection_remover = ConnectionRemover(
@@ -362,19 +366,25 @@ def reset_patchers():
                                 _CertValidatingHTTPSConnection)
 
     try:
-        import tornado.httpclient as http
         import tornado.simple_httpclient as simple
     except ImportError:  # pragma: no cover
         pass
     else:
-        yield mock.patch.object(http, 'AsyncHTTPClient', _AsyncHTTPClient)
+        yield mock.patch.object(
-        yield mock.patch.object(simple, 'SimpleAsyncHTTPClient', _SimpleAsyncHTTPClient)
+            simple.SimpleAsyncHTTPClient,
+            'fetch_impl',
+            _SimpleAsyncHTTPClient_fetch_impl,
+        )
     try:
         import tornado.curl_httpclient as curl
     except ImportError:  # pragma: no cover
         pass
     else:
-        yield mock.patch.object(curl, 'CurlAsyncHTTPClient', _CurlAsyncHTTPClient)
+        yield mock.patch.object(
+            curl.CurlAsyncHTTPClient,
+            'fetch_impl', 
+            _CurlAsyncHTTPClient_fetch_impl,
+        )
 
 
 @contextlib.contextmanager

vcr/request.py

@@ -1,4 +1,4 @@
-from six import BytesIO, binary_type
+from six import BytesIO, text_type
 from six.moves.urllib.parse import urlparse, parse_qsl
 
 
@@ -29,11 +29,9 @@ class Request(object):
         self.uri = uri
         self._was_file = hasattr(body, 'read')
         if self._was_file:
-            self._body = body.read()
+            self.body = body.read()
-            if not isinstance(self._body, binary_type):
-                self._body = self._body.encode('utf-8')
         else:
-            self._body = body
+            self.body = body
         self.headers = {}
         for key in headers:
             self.add_header(key, headers[key])
@@ -44,6 +42,8 @@ class Request(object):
 
     @body.setter
     def body(self, value):
+        if isinstance(value, text_type):
+            value = value.encode('utf-8')
         self._body = value
 
     def add_header(self, key, value):

vcr/stubs/tornado_stubs.py

@@ -1,48 +1,20 @@
 '''Stubs for tornado HTTP clients'''
 from __future__ import absolute_import
 
+import functools
 from six import BytesIO
 
 from tornado import httputil
-from tornado.httpclient import AsyncHTTPClient
 from tornado.httpclient import HTTPResponse
-from tornado.simple_httpclient import SimpleAsyncHTTPClient
 
 from vcr.errors import CannotOverwriteExistingCassetteException
 from vcr.request import Request
 
 
-class _VCRAsyncClient(object):
+def vcr_fetch_impl(cassette, real_fetch_impl):
-    cassette = None
 
-    def __new__(cls, *args, **kwargs):
+    @functools.wraps(real_fetch_impl)
-        from vcr.patch import force_reset
+    def new_fetch_impl(self, request, callback):
-        with force_reset():
-            return super(_VCRAsyncClient, cls).__new__(cls, *args, **kwargs)
-
-    def initialize(self, *args, **kwargs):
-        from vcr.patch import force_reset
-        with force_reset():
-            self.real_client = self._baseclass(*args, **kwargs)
-
-    @property
-    def io_loop(self):
-        return self.real_client.io_loop
-
-    @property
-    def _closed(self):
-        return self.real_client._closed
-
-    @property
-    def defaults(self):
-        return self.real_client.defaults
-
-    def close(self):
-        from vcr.patch import force_reset
-        with force_reset():
-            self.real_client.close()
-
-    def fetch_impl(self, request, callback):
         headers = dict(request.headers)
         if request.user_agent:
             headers.setdefault('User-Agent', request.user_agent)
@@ -74,8 +46,8 @@ class _VCRAsyncClient(object):
             headers,
         )
 
-        if self.cassette.can_play_response_for(vcr_request):
+        if cassette.can_play_response_for(vcr_request):
-            vcr_response = self.cassette.play_response(vcr_request)
+            vcr_response = cassette.play_response(vcr_request)
             headers = httputil.HTTPHeaders()
 
             recorded_headers = vcr_response['headers']
@@ -93,7 +65,7 @@ class _VCRAsyncClient(object):
             )
             return callback(response)
         else:
-            if self.cassette.write_protected and self.cassette.filter_request(
+            if cassette.write_protected and cassette.filter_request(
                 vcr_request
             ):
                 response = HTTPResponse(
@@ -103,8 +75,7 @@ class _VCRAsyncClient(object):
                         "No match for the request (%r) was found. "
                         "Can't overwrite existing cassette (%r) in "
                         "your current record mode (%r)."
-                        % (vcr_request, self.cassette._path,
+                        % (vcr_request, cassette._path, cassette.record_mode)
-                           self.cassette.record_mode)
                     ),
                 )
                 return callback(response)
@@ -123,26 +94,9 @@ class _VCRAsyncClient(object):
                     'headers': headers,
                     'body': {'string': response.body},
                 }
-                self.cassette.append(vcr_request, vcr_response)
+                cassette.append(vcr_request, vcr_response)
                 return callback(response)
 
-            from vcr.patch import force_reset
+            real_fetch_impl(self, request, new_callback)
-            with force_reset():
-                self.real_client.fetch_impl(request, new_callback)
 
-
+    return new_fetch_impl
-class VCRAsyncHTTPClient(_VCRAsyncClient, AsyncHTTPClient):
-    _baseclass = AsyncHTTPClient
-
-
-class VCRSimpleAsyncHTTPClient(_VCRAsyncClient, SimpleAsyncHTTPClient):
-    _baseclass = SimpleAsyncHTTPClient
-
-
-try:
-    from tornado.curl_httpclient import CurlAsyncHTTPClient
-except ImportError:  # pragma: no cover
-    VCRCurlAsyncHTTPClient = None
-else:
-    class VCRCurlAsyncHTTPClient(_VCRAsyncClient, CurlAsyncHTTPClient):
-        _baseclass = CurlAsyncHTTPClient