Models equality depends on self and other be instances of the same cl…

…ass (isinstance instead of is)

bravado_core/model.py

@@ -471,8 +471,11 @@ def __eq__(self, other):
         Two model instances are equal if they have the same type and the same
         properties and values (including additional properties).
         """
-        # Check same type as self
-        if type(self) is not type(other):
+        # Double check is needed to properly deal with polymorphic models
+        # Example: Dog is a discriminated version of Animal.
+        #       assert isinstance(dog, Animal) is True
+        #       assert isinstance(animal, Dog) is False
+        if not isinstance(other, self.__class__) or not isinstance(self, other.__class__):
             return False
 
         # Ignore any '_raw' keys

tests/model/model_test.py

@@ -131,12 +131,20 @@ def test_model_issubclass_inherits_from(pet_type, cat_type):
     assert issubclass(cat_type, pet_type)
 
 
-def test_model_isinstance_model_class_generate_by_different_Spec_object(cat_swagger_spec, cat_type, cat_kwargs):
+def test_model_isinstance_model_class_generated_by_different_Spec_object(cat_swagger_spec, cat_type, cat_kwargs):
     cat = cat_type(**cat_kwargs)
     new_cat_spec = Spec.from_dict(cat_swagger_spec.client_spec_dict)
     assert isinstance(cat, new_cat_spec.definitions['Cat'])
 
 
+def test_model_equality_if_model_class_generated_by_different_Spec_object(cat_swagger_spec, cat_type, cat_kwargs):
+    cat = cat_type(**cat_kwargs)
+    new_cat_spec = Spec.from_dict(cat_swagger_spec.client_spec_dict)
+    new_cat_type = new_cat_spec.definitions['Cat']
+    new_cat = new_cat_type(**cat_kwargs)
+    assert cat == new_cat
+
+
 def test_model_deepcopy(user_type, user_kwargs):
     user = user_type(**user_kwargs)
     user_copy = deepcopy(user)