Inherit "methods" in MethodView

* Current behavior: If a base class inherits MethodView and child class
  inherits without overwriting "methods". The "methods" defined in base
  class would be ignored
* Fix: Inherit all the "methods" defined in base classes if "methods"
  variable is not overwritten

CHANGES.rst

@@ -21,12 +21,15 @@ Unreleased
 -   :func:`send_file` supports :class:`~io.BytesIO` partial content.
     (`#2957`_)
 -   :func:`open_resource` accepts the "rt" file mode. This still does
-    the same thing as "r". (:issue:`3163`)
+    the same thing as "r". :issue:`3163`
+-   The :attr:`MethodView.methods` attribute set in a base class is used
+    by subclasses. :issue:`3138`
 
 .. _#2935: https://github.com/pallets/flask/issues/2935
 .. _#2957: https://github.com/pallets/flask/issues/2957
 .. _#2994: https://github.com/pallets/flask/pull/2994
 .. _#3059: https://github.com/pallets/flask/pull/3059
+.. _#3179: https://github.com/pallets/flask/pull/3179
 
 
 Version 1.0.3

flask/views.py

@@ -120,6 +120,10 @@ class MethodViewType(type):
         if "methods" not in d:
             methods = set()
 
+            for base in bases:
+                if getattr(base, "methods", None):
+                    methods.update(base.methods)
+
             for key in http_method_funcs:
                 if hasattr(cls, key):
                     methods.add(key.upper())

tests/test_views.py

@@ -10,12 +10,11 @@
 """
 
 import pytest
+from werkzeug.http import parse_set_header
 
 import flask
 import flask.views
 
-from werkzeug.http import parse_set_header
-
 
 def common_test(app):
     c = app.test_client()
@@ -199,6 +198,24 @@ def test_endpoint_override(app):
     common_test(app)
 
 
+def test_methods_var_inheritance(app, client):
+    class BaseView(flask.views.MethodView):
+        methods = ["GET", "PROPFIND"]
+
+    class ChildView(BaseView):
+        def get(self):
+            return "GET"
+
+        def propfind(self):
+            return "PROPFIND"
+
+    app.add_url_rule("/", view_func=ChildView.as_view("index"))
+
+    assert client.get("/").data == b"GET"
+    assert client.open("/", method="PROPFIND").data == b"PROPFIND"
+    assert ChildView.methods == {"PROPFIND", "GET"}
+
+
 def test_multiple_inheritance(app, client):
     class GetView(flask.views.MethodView):
         def get(self):