[Python] Python mock.patch: replace a method

I'd like to replace a method in a class with mock:

from unittest.mock import patch

class A(object):
def method(self, string):
print(self, "method", string)

def method2(self, string):
print(self, "method2", string)

with patch.object(A, 'method', side_effect=method2):
a = A()
a.method("string")
a.method.assert_called_with("string")


...but I get insulted by the computer:

TypeError: method2() missing 1 required positional argument: 'string'

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