Add ability to add custom patches to vcr and cassettes.

tests/unit/test_cassettes.py

@@ -7,8 +7,10 @@ import pytest
 import yaml
 
 from vcr.cassette import Cassette
-from vcr.patch import force_reset
 from vcr.errors import UnhandledHTTPRequestError
+from vcr.patch import force_reset
+from vcr.stubs import VCRHTTPSConnection
+
 
 
 def test_cassette_load(tmpdir):
@@ -181,3 +183,21 @@ def test_nesting_context_managers_by_checking_references_of_http_connection():
                     assert httplib.HTTPConnection is original
             assert httplib.HTTPConnection is second_cassette_HTTPConnection
         assert httplib.HTTPConnection is first_cassette_HTTPConnection
+
+
+def test_custom_patchers():
+    class Test(object):
+        attribute = None
+    with Cassette.use('custom_patches', custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
+        assert issubclass(Test.attribute, VCRHTTPSConnection)
+        assert VCRHTTPSConnection is not Test.attribute
+        old_attribute = Test.attribute
+
+        with Cassette.use('custom_patches', custom_patches=((Test, 'attribute', VCRHTTPSConnection),)):
+            assert issubclass(Test.attribute, VCRHTTPSConnection)
+            assert VCRHTTPSConnection is not Test.attribute
+            assert  Test.attribute is not old_attribute
+
+        assert issubclass(Test.attribute, VCRHTTPSConnection)
+        assert VCRHTTPSConnection is not Test.attribute
+        assert  Test.attribute is old_attribute

tests/unit/test_vcr.py

@@ -3,6 +3,7 @@ import pytest
 
 from vcr import VCR, use_cassette
 from vcr.request import Request
+from vcr.stubs import VCRHTTPSConnection
 
 
 def test_vcr_use_cassette():
@@ -74,3 +75,18 @@ def test_fixtures_with_use_cassette(random_fixture):
     # fixtures. It is admittedly a bit strange because the test would never even
     # run if the relevant feature were broken.
     pass
+
+
+def test_custom_patchers():
+    class Test(object):
+        attribute = None
+        attribute2 = None
+    test_vcr = VCR(custom_patches=((Test, 'attribute', VCRHTTPSConnection),))
+    with test_vcr.use_cassette('custom_patches'):
+        assert issubclass(Test.attribute, VCRHTTPSConnection)
+        assert VCRHTTPSConnection is not Test.attribute
+
+    with test_vcr.use_cassette('custom_patches', custom_patches=((Test, 'attribute2', VCRHTTPSConnection),)):
+        assert issubclass(Test.attribute, VCRHTTPSConnection)
+        assert VCRHTTPSConnection is not Test.attribute
+        assert Test.attribute is Test.attribute2

vcr/cassette.py

@@ -87,7 +87,7 @@ class Cassette(object):
                  match_on=(uri, method), filter_headers=(),
                  filter_query_parameters=(), before_record_request=None,
                  before_record_response=None, ignore_hosts=(),
-                 ignore_localhost=()):
+                 ignore_localhost=(), custom_patches=()):
         self._path = path
         self._serializer = serializer
         self._match_on = match_on
@@ -100,6 +100,7 @@ class Cassette(object):
         self.dirty = False
         self.rewound = False
         self.record_mode = record_mode
+        self.custom_patches = custom_patches
 
     @property
     def play_count(self):

vcr/config.py

@@ -12,7 +12,7 @@ from . import filters
 class VCR(object):
 
     def __init__(self, serializer='yaml', cassette_library_dir=None,
-                 record_mode="once", filter_headers=(),
+                 record_mode="once", filter_headers=(), custom_patches=(),
                  filter_query_parameters=(), before_record_request=None,
                  before_record_response=None, ignore_hosts=(),
                  match_on=('method', 'scheme', 'host', 'port', 'path', 'query',),
@@ -43,6 +43,7 @@ class VCR(object):
         self.before_record_response = before_record_response
         self.ignore_hosts = ignore_hosts
         self.ignore_localhost = ignore_localhost
+        self._custom_patches = tuple(custom_patches)
 
     def _get_serializer(self, serializer_name):
         try:
@@ -68,6 +69,9 @@ class VCR(object):
     def use_cassette(self, path, with_current_defaults=False, **kwargs):
         if with_current_defaults:
             return Cassette.use(path, self.get_path_and_merged_config(path, **kwargs))
+        # This is made a function that evaluates every time a cassette is made so that
+        # changes that are made to this VCR instance that occur AFTER the use_cassette
+        # decorator is applied still affect subsequent calls to the decorated function.
         args_getter = functools.partial(self.get_path_and_merged_config, path, **kwargs)
         return Cassette.use_arg_getter(args_getter)
 
@@ -86,7 +90,8 @@ class VCR(object):
             'match_on': self._get_matchers(matcher_names),
             'record_mode': kwargs.get('record_mode', self.record_mode),
             'before_record_request': self._build_before_record_request(kwargs),
-            'before_record_response': self._build_before_record_response(kwargs)
+            'before_record_response': self._build_before_record_response(kwargs),
+            'custom_patches': self._custom_patches + kwargs.get('custom_patches', ())
         }
         return path, merged_config
 

vcr/patch.py

@@ -69,9 +69,12 @@ class CassettePatcherBuilder(object):
         self._class_to_cassette_subclass = {}
 
     def build(self):
-        return itertools.chain(self._httplib(), self._requests(),
-                               self._urllib3(), self._httplib2(),
-                               self._boto())
+        return itertools.chain(
+            self._httplib(), self._requests(), self._urllib3(), self._httplib2(),
+            self._boto(), self._build_patchers_from_mock_triples(
+                self._cassette.custom_patches
+            )
+        )
 
     def _build_patchers_from_mock_triples(self, mock_triples):
         for args in mock_triples:
@@ -88,6 +91,17 @@ class CassettePatcherBuilder(object):
                                      replacement_class))
 
     def _recursively_apply_get_cassette_subclass(self, replacement_dict_or_obj):
+        """One of the subtleties of this class is that it does not directly
+        replace HTTPSConnection with VCRRequestsHTTPSConnection, but a
+        subclass of this class that has cassette assigned to the
+        appropriate value. This behavior is necessary to properly
+        support nested cassette contexts
+
+        This function exists to ensure that we use the same class
+        object (reference) to patch everything that replaces
+        VCRRequestHTTP[S]Connection, but that we can talk about
+        patching them with the raw references instead.
+        """
         if isinstance(replacement_dict_or_obj, dict):
             for key, replacement_obj  in replacement_dict_or_obj.items():
                 replacement_obj = self._recursively_apply_get_cassette_subclass(