EntityMap { public Set<Object> getVertices() { return Collections.unmodifiableSet(backingMap.keySet()); }  boolean putEntity(final Object vertex, final Entity entity); boolean putEntities(final Object vertex, final Set<Entity> entities); Set<Entity> get(final Object vertex); Set<Object> getVertices(); boolean containsVertex(final Object vertex); String toStringFull(); @Override String toString();  }
@Test public void shouldGetEntities() { final EntityMap entityMap = getEntityMap(); final Set<Object> results = entityMap.getVertices(); assertThat(results, hasItems(1)); }
@Test public void shouldGetEmptyEntitySet() { final EntityMap entityMap = new EntityMap(); final Set<Object> results = entityMap.getVertices(); assertThat(results, is(empty())); }
@Test public void shouldGetVertices() { final EntityMap entityMap = getEntityMap(); final Set<Object> results = entityMap.getVertices(); assertThat(results, hasItems(1, 2, 3, 4, 5, 6)); }