@Test
  public void shouldNotEvaluateToEqualDifferentId() {
    final Vertex v = mock(Vertex.class);
    when(v.id()).thenReturn("2");
    when(v.label()).thenReturn("l");

    final DetachedVertex mv1 = DetachedVertex.detach(v);
    assertFalse(mv1.equals(this.mv));
  }
  @Before
  public void setup() {
    final Vertex v = mock(Vertex.class);
    when(v.id()).thenReturn("1");
    when(v.label()).thenReturn("l");

    this.mv = DetachedVertex.detach(v);
  }
 @Test(expected = IllegalArgumentException.class)
 public void shouldNotConstructWithNullElement() {
   DetachedVertex.detach(null);
 }