use callable classes instead of function for funcopy

Author: chaope

Lib/unittest/mock.py

@@ -199,9 +199,13 @@ def checksig(*args, **kwargs):
     if not name.isidentifier():
         name = 'funcopy'
     context = {'_checksig_': checksig, 'mock': mock}
-    src = """def %s(*args, **kwargs):
-    _checksig_(*args, **kwargs)
-    return mock(*args, **kwargs)""" % name
+    src = """class %s:
+    def __call__(*args, **kwargs):
+        _checksig_(*args, **kwargs)
+        return mock(*args, **kwargs)
+    def call_count(self):
+        return len(self.call_args_list)
+    %s = %s()""" % name
     exec (src, context)
     funcopy = context[name]
     _setup_func(funcopy, mock, sig)