@Test
    public void testSuccess() {
      String id = "entity-id";
      String kind = "entity-kind";

      TombstoneEntity entity = tombstoneBackend.create(kind, id);
      assertThat(entity, notNullValue());
      assertThat(entity, is(tombstoneBackend.getByEntityId(id)));

      tombstoneBackend.delete(entity);
      assertThat(tombstoneBackend.getByEntityId(id), nullValue());
    }
    @Test(
        expectedExceptions = RuntimeException.class,
        expectedExceptionsMessageRegExp = "Multiple tombstones for entity: entity-id")
    public void testMultipleDocuments() {
      String id = "entity-id";
      String kind = "entity-kind";
      buildTombstones(3, id, kind);

      tombstoneBackend.getByEntityId(id);
    }
    @Test
    public void testOneDocument() {
      String id = "entity-id";
      String kind = "entity-kind";
      buildTombstones(1, id, kind);

      TombstoneEntity entity = tombstoneBackend.getByEntityId(id);
      assertThat(entity, notNullValue());
      assertThat(entity.getEntityId(), is(id));
      assertThat(entity.getEntityKind(), is(kind));
      assertThat(entity.getTombstoneTime(), notNullValue());
    }
 @Test
 public void testNoDocuments() {
   assertThat(tombstoneBackend.getByEntityId("missing-id"), nullValue());
 }