@Test
    @LoadGraphWith(GRATEFUL)
    public void g_V_outXfollowedByX_group_byXsongTypeX_byXbothE_group_byXlabelX_byXweight_sumXX() {
        final Traversal<Vertex, Map<String, Map<String, Number>>> traversal = get_g_V_outXfollowedByX_group_byXsongTypeX_byXbothE_group_byXlabelX_byXweight_sumXX();
        printTraversalForm(traversal);
        final Map<String, Map<String, Number>> map = traversal.next();
        assertFalse(traversal.hasNext());
        assertEquals(3, map.size());
        assertTrue(map.containsKey(""));
        assertTrue(map.containsKey("original"));
        assertTrue(map.containsKey("cover"));
        //
        Map<String, Number> subMap = map.get("");
        assertEquals(1, subMap.size());
        assertEquals(179350, subMap.get("followedBy").intValue());
        //
        subMap = map.get("original");
        assertEquals(1, subMap.size());
        assertEquals(2185613, subMap.get("followedBy").intValue());
        //
        subMap = map.get("cover");
        assertEquals(1, subMap.size());
        assertEquals(777982, subMap.get("followedBy").intValue());
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/GroupTest.java