Make insertion order of SwaggerDict extra parameters consistent

src/drf_yasg/openapi.py

@@ -116,7 +116,7 @@ class SwaggerDict(OrderedDict):
         which would result in the extra attributes being added first. For this reason, we defer the insertion of the
         attributes and require that subclasses call ._insert_extras__ at the end of their __init__ method.
         """
-        for attr, val in self._extras__.items():
+        for attr, val in sorted(self._extras__.items()):
             setattr(self, attr, val)
 
     @staticmethod

tests/test_swaggerdict.py

@@ -1,3 +1,6 @@
+from collections import OrderedDict
+from random import shuffle
+
 from drf_yasg import openapi
 
 
@@ -51,3 +54,15 @@ def test_trailing_underscore_stripped():
     del sd.in_
     assert 'in' not in sd
     assert not hasattr(sd, 'in__')
+
+
+def test_extra_ordering():
+    """Insertion order should also be consistent when setting undeclared parameters (kwargs) in SwaggerDict"""
+    extras = [('beta', 1), ('alpha', 2), ('omega', 3), ('gamma', 4)]
+    shuffled_extras = list(extras)
+    shuffle(shuffled_extras)
+
+    s1 = openapi.SwaggerDict(**OrderedDict(extras))
+    s2 = openapi.SwaggerDict(**OrderedDict(shuffled_extras))
+
+    assert list(s1.items()) == list(s2.items())