Python - Testing an abstract base class

Question

I am looking for ways / best practices on testing methods defined in an abstract base class. One thing I can think of directly is performing the test on all concrete subclasses of the base class, but that seems excessive at some times.

Consider this example:

import abc  class Abstract(object):      __metaclass__ = abc.ABCMeta      @abc.abstractproperty     def id(self):         return         @abc.abstractmethod     def foo(self):         print "foo"      def bar(self):         print "bar" 

Is it possible to test bar without doing any subclassing?

Answer 1

In newer versions of Python you can use unittest.mock.patch()

class MyAbcClassTest(unittest.TestCase):      @patch.multiple(MyAbcClass, __abstractmethods__=set())     def test(self):          self.instance = MyAbcClass() # Ha!