@Test
public void testIsCacheLoaded()
{

    Set<Animal> animals = new HashSet<>();
    animals.add( new Animal( 1, "horse" ) );
    animals.add( new Animal( 3, "cat" ) );
    CachingMap<Integer, Animal> cache = new CachingMap<Integer, Animal>();
    
    assertFalse( cache.isCacheLoaded() );
    
    cache.load( animals, a -> a.getId() );
    assertTrue( cache.isCacheLoaded() );
}