@Test
    @LoadGraphWith(LoadGraphWith.GraphData.CLASSIC)
    public void shouldReadWriteVerticesNoEdgesToGraphSONManual() throws Exception {
        assumeThat(ioType, startsWith("graphson"));
        try (final ByteArrayOutputStream os = new ByteArrayOutputStream()) {
            final GraphWriter writer = writerMaker.apply(graph);
            writer.writeVertices(os, g.V().has("age", P.gt(30)));

            final AtomicInteger called = new AtomicInteger(0);
            final GraphReader reader = readerMaker.apply(graph);
            try (final BufferedReader br = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(os.toByteArray())))) {
                String line = br.readLine();
                reader.readVertex(new ByteArrayInputStream(line.getBytes()),
                        attachable -> {
                            called.incrementAndGet();
                            return mock(Vertex.class);
                        });

                line = br.readLine();
                reader.readVertex(new ByteArrayInputStream(line.getBytes()),
                        detachedVertex -> {
                            called.incrementAndGet();
                            return mock(Vertex.class);
                        });
            }

            assertEquals(2, called.get());
        }
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/io/IoVertexTest.java