'L{FDDetector._getImplementation} returns the last method from its
C{_implementations} list if none of the implementations manage to return
results which reflect a newly opened file descriptor.'

def test_selectLast(self):

    def failWithWrongResults():
        return [3, 5, 9]
    def failWithOtherWrongResults():
        return [0, 1, 2]
    self.detector._implementations = [failWithWrongResults, failWithOtherWrongResults]
    self.assertIs(failWithOtherWrongResults, self.detector._getImplementation())
