### Question:
RequestScopeExtractor implements AttributeExtractor { @Override public Enumeration<String> getKeys() { return request.getAttributeNames(); } RequestScopeExtractor(PortletRequest request); @Override void setValue(String name, Object value); @Override void removeValue(String name); @Override Enumeration<String> getKeys(); @Override Object getValue(String key);  }### Answer:
@SuppressWarnings("unchecked") @Test public void testGetKeys() { Enumeration<String> keys = createMock(Enumeration.class); expect(request.getAttributeNames()).andReturn(keys); replay(request, keys); assertEquals(keys, extractor.getKeys()); verify(request, keys); }