Can I fake/mock the type of my mock objects in python unittests

Question

In my python code I check the type of one of the parameters to make sure it is of the type I expect. For instance:

def myfunction(dbConnection):     if (type(dbConnection)<>bpgsql.Connection):         r['error'] += ' invalid database connection' 

I want to pass a mock connection for testing purposes. Is there a way to make the mock object pretend to be of the correct type?

Answer 1

With all due respect, It looks like you guys are not quite right!

I can use duck typing as said, but there is a way to do what I intended to do in the first place:

from http://docs.python.org/dev/library/unittest.mock.html

Mock objects that use a class or an instance as a spec or spec_set are able to pass isintance tests:

>>> >>> mock = Mock(spec=SomeClass) >>> isinstance(mock, SomeClass) True >>> mock = Mock(spec_set=SomeClass()) >>> isinstance(mock, SomeClass) True 

so my example code would be like:

m = mock.MagicMock(spec=bpgsql.Connection) isinstance(m, bpgsql.Connection)  

this returns True

All that said, I am not arguing for strict type checking in python, I say if you need to check it you can do it and it works with testing and mocking too.