### Question:
WSCXMLKnowledgeBase implements HierarchicalKnowledgeBase, Serializable { @Override public Set<Concept> getSubclasses(Concept concept) { return ImmutableSet.copyOf(this.subclasses.get(concept)); } WSCXMLKnowledgeBase(InputStream xmlTaxonomyStream);  WSCXMLKnowledgeBase(String xmlTaxonomy);  WSCXMLKnowledgeBase(File xmlTaxonomyFile);  WSCXMLKnowledgeBase(); @Override Concept getConcept(String id); @Override Instance getInstance(String id); @Override Set<Concept> getSubclasses(Concept concept); @Override Set<Concept> getSuperclasses(Concept concept); boolean equivalent(Concept x, Concept y); boolean isSubclass(Concept x, Concept y); boolean isSuperclass(Concept x, Concept y); @Override Concept resolveInstance(Instance instance); Set<Instance> getInstances(Concept concept); Set<Concept> getConcepts(); Set<Instance> getInstances();  }### Answer:
@Test public void testGetSubclasses() throws Exception { Set<String> expected = Sets.newHashSet("con430174676", "con983993996", "con1190652189", "con1608884093", "con1263361472", "con1954406752", "con1817180792", "con775697297", "con777335841", "con501245415", "con985632540", "con567400598", "con428536132", "con1952768208", "con15219784", "con1398948888", "con1744471509", "con1537813354", "con1331155161", "con1746110053"); Set<Concept> subclasses = kb.getSubclasses(kb.getConcept("con2025477491")); assertEquals(expected.size(), subclasses.size()); for(Concept subclass : subclasses){ assertTrue(expected.contains(subclass.getID())); } }