Pass kwargs through to http client fetch.

docs/history.rst

@@ -1,6 +1,11 @@
 Version History
 ===============
 
+Next Release
+------------
+- Pass keyword parameters through to the underlying HTTPClient fetch method.
+  This enables niceties like streaming callback support
+
 `2.3.1`_ Apr 7, 2020
 --------------------
 - Address `#27`_ by using the shortest appropriate timeout

sprockets/mixins/http/__init__.py

@@ -272,7 +272,8 @@ class HTTPClientMixin:
                          user_agent=None,
                          validate_cert=True,
                          allow_nonstandard_methods=False,
-                         dont_retry=None):
+                         dont_retry=None,
+                         **kwargs):
         """Perform a HTTP request
 
         Will retry up to ``self.MAX_HTTP_RETRIES`` times.
@@ -304,6 +305,8 @@ class HTTPClientMixin:
             to the HTTP spec.
         :param set dont_retry: A list of status codes that will not be retried
             if an error is returned. Default: set({})
+        :param kwargs: additional keyword parameters are passed to
+            :meth:`tornado.httpclient.AsyncHTTPClient.fetch`
         :rtype: HTTPResponse
 
         """
@@ -353,7 +356,8 @@ class HTTPClientMixin:
                     max_redirects=max_redirects,
                     raise_error=False,
                     validate_cert=validate_cert,
-                    allow_nonstandard_methods=allow_nonstandard_methods)
+                    allow_nonstandard_methods=allow_nonstandard_methods,
+                    **kwargs)
             except (OSError, httpclient.HTTPError) as error:
                 response.append_exception(error)
                 LOGGER.warning(

tests.py

@@ -615,3 +615,16 @@ class MixinTestCase(testing.AsyncHTTPTestCase):
         self.assertAlmostEqual(response.duration,
                                response.attempts * 0.25,
                                places=1)
+
+    @testing.gen_test
+    def test_that_kwargs_are_passed_through(self):
+        chunks = []
+
+        def streaming_callback(chunk):
+            chunks.append(chunk)
+
+        response = yield self.mixin.http_fetch(
+            self.get_url('/test'),
+            streaming_callback=streaming_callback)
+        self.assertTrue(response.ok)
+        self.assertGreater(len(chunks), 0)