@Test
    public void shouldApplyIdOnElement() {
        final Element e = mock(Element.class);
        when(e.id()).thenReturn(100l);

        assertEquals(100l, T.id.apply(e));
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/structure/TTest.java