### Question:
ResourceLoader { public synchronized void start() { if (started.get()) { throw new LionEngineException(ERROR_STARTED); } started.set(true); thread.start(); } ResourceLoader(); synchronized void add(T key, Resource resource); synchronized void start(); synchronized void await(); synchronized Map<T, Resource> get(); boolean isFinished();  }### Answer:
@Test void testAlreadyStarted() { final ResourceLoader<Type> resourceLoader = new ResourceLoader<>(); resourceLoader.start(); assertThrows(() -> resourceLoader.start(), ResourceLoader.ERROR_STARTED); }