Fix bug that prevents returning Flask.Responses

which https://flask-rebar.readthedocs.io/en/latest/quickstart/basics.html#marshaling
promises should be supported.

Also add a test case that fails without this fix.

flask_rebar/rebar.py

@@ -71,7 +71,7 @@ def _unpack_view_func_return_value(rv):
 
     This imitates Flask's own `Flask.make_response` method.
 
-    :param Optional[tuple] rv: (body, status, headers), (body, status), or (body, headers)
+    :param rv: (body, status, headers), (body, status), (body, headers), or body
     :return: (body, status, headers)
     :rtype: tuple
     """
@@ -146,6 +146,9 @@ def wrapped(*args, **kwargs):
         if not response_body_schema:
             return rv
 
+        if isinstance(rv, current_app.response_class):
+            return rv
+
         data, status_code, headers = _unpack_view_func_return_value(rv)
 
         schema = response_body_schema[status_code]  # May raise KeyError.

tests/test_rebar.py

@@ -11,7 +11,7 @@
 import unittest
 
 import marshmallow as m
-from flask import Flask
+from flask import Flask, make_response
 
 from flask_rebar import messages
 from flask_rebar import HeaderApiKeyAuthenticator, SwaggerV3Generator
@@ -241,6 +241,19 @@ def update_foo(foo_uid):
         )
         self.assertEqual(resp.status_code, 400)
 
+    def test_flask_response_instance_interop(self):
+        rebar = Rebar()
+        registry = rebar.create_handler_registry()
+
+        @registry.handles(rule="/foo", response_body_schema={302: None})
+        def foo():
+            return make_response(("Redirecting", 302, {"Location": "http://foo.com"}))
+
+        app = create_rebar_app(rebar)
+        resp = app.test_client().get(path="/foo")
+        self.assertEqual(resp.status_code, 302)
+        self.assertEqual(resp.headers["Location"], "http://foo.com")
+
     def test_validate_query_parameters(self):
         rebar = Rebar()
         registry = rebar.create_handler_registry()