@Test
public void testVariantRequired() throws IOException, SchemaSyntaxException {

  OSLSchema schema = (OSLSchema) readSchema("in", "variant.xml");
  TopicIF type = makeType("#type");
  TopicIF instance = builder.makeTopic();
  instance.addType(type);
  TopicNameIF bn = builder.makeTopicName(instance, "Testtopic");
  validate(schema, bn, null);
}