Python Patch/Mock class method but still call original method

Question

I want to use patch to record all function calls made to a function in a class for a unittest, but need the original function to still run as expected. I created a dummy code example below:

from mock import patch  class A(object):     def __init__(self):         self._a = 1  class B(A):     def __init__(self):         super(B, self).__init__() # TypeError: super() argument 1 must be type, not MagicMock         self._b = 11      def bar(self, b):         self._b = self._b + 1 + b      def foo(self, b):         self.bar(b)  class MockB(B):     def foo(self, b):         super(MockB, self).foo(self, b)  @patch('main.B') def main(b_class):     b_class.side_effect = MockB      b = B()      print b._b # 11     b.foo(0)     print b._b # 12  main() 

In my case, the instance of the class b = B() is not actually in the main function but in another module, so I can't Mock the instance. I need it to generically be a decorator for all instances of B.

Summary: I am not sure how to individually mock the class method on it's own, but still call the original method. After, I want to use something like call_args_list where I can see all calls made to foo().

Answer 1

I think you are looking for the wraps Mock parameter. Search the official documentation for wraps. Accessing attributes returns a mock object. Calling methods gives the real method result instead, if a return value is not configured for the mock.