Python - Testing an abstract base class

python oop testing abc
bow picture bow · Mar 18, 2012 · Viewed 20.5k times · Source

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

Mariusz Jamro picture Mariusz Jamro · Feb 26, 2015

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!

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