Trac #31182: doctests added for __setstate__ and __getstate__

src/sage/structure/mutability.pyx

@@ -121,6 +121,30 @@ cdef class Mutability:
     def __getstate__(self):
         r"""
         Get the current state of ``self`` including the mutability status.
+        
+        TESTS::
+        
+            sage: class A(SageObject, Mutability):
+            ....:     def __init__(self, val):
+            ....:         self._val = val
+            ....:     def change(self, val):
+            ....:         self._require_mutable()
+            ....:         self._val = val
+            ....:     def __hash__(self):
+            ....:         self._require_immutable()
+            ....:         return hash(self._val)
+            sage: a = A(4)
+            sage: a.__dict__
+            {'_val': 4}
+            sage: a.__getstate__()
+            {'_is_immutable': False, '_val': 4}
+            sage: a.__reduce__()  # indirect doctest
+            (<function _reconstructor at ...>,
+             (<class '__main__.A'>,
+              <class 'sage.structure.sage_object.SageObject'>,
+              <sage.structure.sage_object.SageObject object at ...>),
+             {'_is_immutable': False, '_val': 4})
+            
         """
         state = getattr(self, '__dict__', {})
         state['_is_immutable'] = self._is_immutable
@@ -130,6 +154,30 @@ cdef class Mutability:
         r"""
         Set the state of ``self`` from the dictionary ``state`` including the
         mutability status.
+
+        TESTS::
+
+            sage: class A(SageObject, Mutability):
+            ....:     def __init__(self, val):
+            ....:         self._val = val
+            ....:     def change(self, val):
+            ....:         self._require_mutable()
+            ....:         self._val = val
+            ....:     def __hash__(self):
+            ....:         self._require_immutable()
+            ....:         return hash(self._val)
+            sage: a = A(4)
+            sage: a.is_immutable()
+            False
+            sage: d = a.__getstate__(); d
+            {'_is_immutable': False, '_val': 4}
+            sage: d['_is_immutable'] = True
+            sage: a.__setstate__(d)
+            sage: a.is_immutable()
+            True
+            sage: a.__getstate__()
+            {'_is_immutable': True, '_val': 4}
+
         """
         if hasattr(self, '__dict__'):
             self.__dict__ = state