public void testInterfaceDefHandlerWithExtension() throws Exception {
XMLParser parser = XMLParser.getInstance();
DefDescriptor<InterfaceDef> descriptor = DefDescriptorImpl.getInstance("test:fakeparser", InterfaceDef.class);
StringSource<InterfaceDef> source = new StringSource<>(descriptor,
"<aura:interface extends='aura:testinterfaceparent'></aura:interface>", "myID", Format.XML);
InterfaceDef def = parser.parse(descriptor, source);
assertEquals(1, def.getExtendsDescriptors().size());
assertEquals("testinterfaceparent", def.getExtendsDescriptors().iterator().next().getName());
}