@Test
        @FeatureRequirement(featureClass = Graph.Features.EdgeFeatures.class, feature = Graph.Features.EdgeFeatures.FEATURE_ADD_EDGES)
        @FeatureRequirement(featureClass = Graph.Features.VertexFeatures.class, feature = Graph.Features.VertexFeatures.FEATURE_ADD_VERTICES)
        public void shouldReturnOutThenInOnVertexIterator() {
            final Vertex a = graph.addVertex();
            final Vertex b = graph.addVertex();
            final Edge e = a.addEdge("knows", b);
            assertEquals(a, e.outVertex());
            assertEquals(b, e.inVertex());
            final Iterator<Vertex> iterator = e.vertices(Direction.BOTH);
            assertTrue(iterator.hasNext());
            assertEquals(a, iterator.next());
            assertTrue(iterator.hasNext());
            assertEquals(b, iterator.next());
            assertFalse(iterator.hasNext());
        }
@author Stephen Mallette (http://stephen.genoprime.com)
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/EdgeTest.java