Fix for #174 to prevent filters from corrupting request

tests/integration/test_filter.py

@@ -142,3 +142,24 @@ def test_decompress_regular(tmpdir, httpbin):
         resp = urlopen(url).read()
         assert_cassette_has_one_response(cass)
     assert_is_json(resp)
+
+
+def test_before_record_request_corruption(tmpdir, httpbin):
+    """Modifying request in before_record_request should not affect outgoing request"""
+
+    def before_record(request):
+        request.headers.clear()
+        request.body = b""
+        return request
+
+    req = Request(
+        httpbin.url + "/post",
+        data=urlencode({"test": "exists"}).encode(),
+        headers={"X-Test": "exists"},
+    )
+    cass_file = str(tmpdir.join("modified_response.yaml"))
+    with vcr.use_cassette(cass_file, before_record_request=before_record):
+        resp = json.loads(urlopen(req).read())
+
+    assert resp["headers"]["X-Test"] == "exists"
+    assert resp["form"]["test"] == "exists"

vcr/config.py

@@ -219,7 +219,7 @@ class VCR:
             filter_functions.extend(before_record_request)
 
         def before_record_request(request):
-            request = copy.copy(request)
+            request = copy.deepcopy(request)
             for function in filter_functions:
                 if request is None:
                     break