APIRequestor: don't mutate incoming multipart headers

stripe/api_requestor.py

@@ -3,7 +3,7 @@
 import json
 import platform
 import time
-from typing import Optional, Tuple
+from typing import Dict, Optional, Tuple
 import uuid
 import warnings
 from collections import OrderedDict
@@ -296,6 +296,10 @@ def request_raw(
         Mechanism for issuing an API call
         """
 
+        supplied_headers_dict: Optional[Dict[str, str]] = (
+            dict(supplied_headers) if supplied_headers is not None else None
+        )
+
         if self.api_key:
             my_api_key = self.api_key
         else:
@@ -327,14 +331,14 @@ def request_raw(
             post_data = None
         elif method == "post":
             if (
-                supplied_headers is not None
-                and supplied_headers.get("Content-Type")
+                supplied_headers_dict is not None
+                and supplied_headers_dict.get("Content-Type")
                 == "multipart/form-data"
             ):
                 generator = MultipartDataGenerator()
                 generator.add_params(params or {})
                 post_data = generator.get_post_data()
-                supplied_headers[
+                supplied_headers_dict[
                     "Content-Type"
                 ] = "multipart/form-data; boundary=%s" % (generator.boundary,)
             else:
@@ -347,8 +351,8 @@ def request_raw(
             )
 
         headers = self.request_headers(my_api_key, method)
-        if supplied_headers is not None:
-            for key, value in supplied_headers.items():
+        if supplied_headers_dict is not None:
+            for key, value in supplied_headers_dict.items():
                 headers[key] = value
 
         util.log_info("Request to Stripe api", method=method, path=abs_url)

tests/api_resources/test_file.py

@@ -28,7 +28,11 @@ def test_is_retrievable(self, request_mock):
         request_mock.assert_requested("get", "/v1/files/%s" % TEST_RESOURCE_ID)
         assert isinstance(resource, stripe.File)
 
-    def test_is_creatable(self, setup_upload_api_base, request_mock):
+    def test_is_creatable(self, mocker):
+        hc = mocker.Mock(stripe.http_client.HTTPClient)
+        hc.name = "mockclient"
+        stripe.default_http_client = hc
+        hc.request_with_retries.return_value = ('{"object": "file"}', 200, {})
         stripe.multipart_data_generator.MultipartDataGenerator._initialize_boundary = (
             lambda self: 1234567890
         )
@@ -38,14 +42,19 @@ def test_is_creatable(self, setup_upload_api_base, request_mock):
             file=test_file,
             file_link_data={"create": True},
         )
-        request_mock.assert_api_base(stripe.upload_api_base)
-        request_mock.assert_requested(
-            "post",
-            "/v1/files",
-            headers={
-                "Content-Type": "multipart/form-data; boundary=1234567890"
-            },
+        method, url, headers, body = hc.request_with_retries.call_args[0]
+        assert method == "post"
+        assert url.endswith("/v1/files")
+        assert (
+            headers["Content-Type"]
+            == "multipart/form-data; boundary=1234567890"
         )
+        parts = body.split(b"--1234567890")
+        assert len(parts) == 5
+        assert parts[0] == b""
+        assert b'name="purpose"' in parts[1]
+        assert b'name="file"' in parts[2]
+        assert b'name="file_link_data[create]"' in parts[3]
         assert isinstance(resource, stripe.File)
 
     def test_create_respects_stripe_version(

tests/test_api_requestor.py

@@ -761,6 +761,7 @@ def test_raw_request_with_file_param(self, requestor, mock_response):
         supplied_headers = {"Content-Type": "multipart/form-data"}
         mock_response("{}", 200)
         requestor.request("post", "/v1/files", params, supplied_headers)
+        assert supplied_headers["Content-Type"] == "multipart/form-data"
 
 
 class TestDefaultClient(object):