HexTable implements QuadTable { @Override public Stream<Node> listGraphNodes() { return indexBlock().get(GSPO).listGraphNodes(); }  @Override Stream<Quad> find(final Node g, final Node s, final Node p, final Node o); @Override void add(final Quad q); @Override void delete(final Quad q); @Override Stream<Node> listGraphNodes(); @Override Stream<Quad> findInUnionGraph(final Node s, final Node p, final Node o); @Override void begin(final ReadWrite rw); @Override void end(); @Override void commit(); @Override void clear();  }
@Test public void testListGraphNodes() { final int nodesToTry = 50; final HexTable index = new HexTable(); final Set<Node> graphNodes = new HashSet<>(nodesToTry); index.begin(null); for (int i = 0; i < nodesToTry; i++) { final Node node = createBlankNode(); index.add(Quad.create(node, node, node, node)); graphNodes.add(node); assertEquals(graphNodes, index.listGraphNodes().collect(toSet())); } index.end(); }