tweak copy and add fields copy test

pydantic/main.py

@@ -136,23 +136,21 @@ def construct(cls, **values):
 
     def copy(self, *, include: Set[str]=None, exclude: Set[str]=None, update: Dict[str, Any]=None):
         """
-        Duplicate a model, optionally choose which fields to include, exclude and change
-        :param include: fields to include in new model.
+        Duplicate a model, optionally choose which fields to include, exclude and change.
+
+        :param include: fields to include in new model
         :param exclude: fields to exclude from new model, as with values this takes precedence over include
         :param update: values to change/add in the new model. Note: the data is not validated before creating
-            the new model: you should trust this data.
+            the new model: you should trust this data
         :return: new model instance
         """
         if include is None and exclude is None and update is None:
-            # skip constructing values if no arguments are set
+            # skip constructing values if no arguments are passed
             v = self.__values__
         else:
             exclude = exclude or set()
             v = {
-                **{
-                    k: v for k, v in self.__values__.items()
-                    if k not in exclude and (not include or k in include)
-                },
+                **{k: v for k, v in self.__values__.items() if k not in exclude and (not include or k in include)},
                 **(update or {})
             }
         return self.__class__.construct(**v)

tests/test_construction.py

@@ -32,6 +32,7 @@ def test_simple_copy():
     assert m.a == m2.a == 24
     assert m.b == m2.b == 10
     assert m == m2
+    assert m.__fields__ == m2.__fields__
 
 
 class ModelTwo(BaseModel):
@@ -97,6 +98,7 @@ def test_simple_pickle():
     assert m is not m2
     assert tuple(m) == (('a', 24.0), ('b', 10))
     assert tuple(m2) == (('a', 24.0), ('b', 10))
+    assert m.__fields__ == m2.__fields__
 
 
 def test_recursive_pickle():
@@ -106,3 +108,4 @@ def test_recursive_pickle():
 
     assert m.d.a == 123.45
     assert m2.d.a == 123.45
+    assert m.__fields__ == m2.__fields__