def testCount(self):

        assertEqual = self.assertEqual

        # Regular input
        values = ["A", "B", "B", "C"]
        aggregate = S3GroupAggregate("count", "Example", values)
        assertEqual(aggregate.result, 3)

        # None gives always None
        values = None
        aggregate = S3GroupAggregate("count", "Example", values)
        assertEqual(aggregate.result, None)

        # Invalid input: non-iterable type
        values = 17
        aggregate = S3GroupAggregate("count", "Example", values)
        assertEqual(aggregate.result, None)

    # -------------------------------------------------------------------------
A subscription identifier in the subscription should be parsed, too.
dataset/ETHPy150Open sahana/eden/modules/unit_tests/s3/s3grouped.py/S3GroupAggregateTests.testCount--crossover with--dataset/ETHPy150Open ralphm/wokkel/wokkel/test/test_pubsub.py/SubscriptionTest.test_fromElementWithSubscriptionIdentifier