Add the alter_live_response option

Fixes kevin1024#544

vcr/cassette.py

@@ -180,6 +180,7 @@ def __init__(
         match_on=(uri, method),
         before_record_request=None,
         before_record_response=None,
+        alter_live_response=False,
         custom_patches=(),
         inject=False,
         allow_playback_repeats=False,
@@ -191,6 +192,7 @@ def __init__(
         self._before_record_request = before_record_request or (lambda x: x)
         log.info(self._before_record_request)
         self._before_record_response = before_record_response or (lambda x: x)
+        self._alter_live_response = alter_live_response
         self.inject = inject
         self.record_mode = record_mode
         self.custom_patches = custom_patches
@@ -229,10 +231,6 @@ def append(self, request, response):
         request = self._before_record_request(request)
         if not request:
             return
-        # Deepcopy is here because mutation of `response` will corrupt the
-        # real response.
-        response = copy.deepcopy(response)
-        response = self._before_record_response(response)
         if response is None:
             return
         self.data.append((request, response))

vcr/config.py

@@ -42,6 +42,7 @@ def __init__(
         ignore_localhost=False,
         filter_headers=(),
         before_record_response=None,
+        alter_live_response=None,
         filter_post_data_parameters=(),
         match_on=("method", "scheme", "host", "port", "path", "query"),
         before_record=None,
@@ -75,6 +76,7 @@ def __init__(
         self.filter_post_data_parameters = filter_post_data_parameters
         self.before_record_request = before_record_request or before_record
         self.before_record_response = before_record_response
+        self.alter_live_response = alter_live_response
         self.ignore_hosts = ignore_hosts
         self.ignore_localhost = ignore_localhost
         self.inject_cassette = inject_cassette
@@ -145,6 +147,7 @@ def add_cassette_library_dir(path):
             "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),
+            "alter_live_response": self.alter_live_response,
             "custom_patches": self._custom_patches + kwargs.get("custom_patches", ()),
             "inject": kwargs.get("inject_cassette", self.inject_cassette),
             "path_transformer": path_transformer,

vcr/stubs/__init__.py

@@ -1,5 +1,6 @@
 """Stubs for patching HTTP and HTTPS requests"""
 
+import copy
 import logging
 from http.client import (
     HTTPConnection,
@@ -249,16 +250,24 @@ def getresponse(self, _=False, **kwargs):
                 )
 
             # get the response
-            response = self.real_connection.getresponse()
+            live_response = self.real_connection.getresponse()
 
             # put the response into the cassette
-            response = {
-                "status": {"code": response.status, "message": response.reason},
-                "headers": serialize_headers(response),
-                "body": {"string": response.read()},
+            live_response = {
+                "status": {"code": live_response.status, "message": live_response.reason},
+                "headers": serialize_headers(live_response),
+                "body": {"string": live_response.read()},
             }
+            # Deepcopy is here because mutation of `response` will corrupt the
+            # real response.
+            response = copy.deepcopy(live_response)
+            response = self.cassette._before_record_response(response)
+
             self.cassette.append(self._vcr_request, response)
-        return VCRHTTPResponse(response)
+        if self.cassette._alter_live_response:
+            return VCRHTTPResponse(response)
+        else:
+            return VCRHTTPResponse(live_response)
 
     def set_debuglevel(self, *args, **kwargs):
         self.real_connection.set_debuglevel(*args, **kwargs)