update doc

Author: chaope

Doc/library/unittest.mock.rst

@@ -532,7 +532,8 @@ the *new_callable* argument to :func:`patch`.
 
     .. attribute:: call_count
 
-        An integer telling you how many times the mock object has been called:
+        An integer telling you how many times the mock object has been called,
+        it is the length of call_args_list:
 
             >>> mock = Mock(return_value=None)
             >>> mock.call_count
@@ -541,6 +542,8 @@ the *new_callable* argument to :func:`patch`.
             >>> mock()
             >>> mock.call_count
             2
+            >>> mock.call_count == len(mock.call_args_list)
+            True
 
     .. attribute:: return_value