'If I{service_identity} cannot be imported then
L{_selectVerifyImplementation} returns L{simpleVerifyHostname} and
L{SimpleVerificationError}.'

def test_dependencyMissing(self):

    with SetAsideModule('service_identity'):
        sys.modules['service_identity'] = None
        result = sslverify._selectVerifyImplementation()
        expected = (sslverify.simpleVerifyHostname, sslverify.SimpleVerificationError)
        self.assertEqual(expected, result)
