@Test
public void testTypeWithNullValue() {

    List<MetricSchemaRecord> records = new ArrayList<>();
    records.add(new MetricSchemaRecord(null, "scope1", "metric0", "source", "unittest"));
    records.add(new MetricSchemaRecord(null, "scope1", "metric1", "source", "unittest"));
    records.add(new MetricSchemaRecord(null, "scope2", "metric2", "source", "unittest"));
    records.add(new MetricSchemaRecord(null, "scope2", "metric3", "source", "unittest"));
    records.add(new MetricSchemaRecord(null, "scope2", "metric4", "source", "unittest"));
    SortedSet<String> ns = MetricSchemaRecordTokenizer.GetUniqueTokens(records, SchemaService.RecordType.NAMESPACE, 0);
    assertTrue(ns.size() == 0);
}