SimpleContainer implements Containerlike<T> { @Override public Collection<T> findSimilar(ThingTypeCheck<T>judge) { List<T> ret = new ArrayList<>(); if (judge == null) { throw new NullPointerException("Need a judge."); } for (T thing : this) { if (judge.isSufficient(thing)) { ret.add(thing); } } return ret; } SimpleContainer();  SimpleContainer(ThingTypeCheck<T> verifier);  SimpleContainer(ThingTypeCheck<T> verifier, int limit); @Override boolean canFit(T thing); @Override Collection<T> findSimilar(ThingTypeCheck<T>judge); @Override Collection<T> removeUnfit(); @Override boolean hasUnfit(); @Override void setVerifier(ThingTypeCheck<T> verifier); @Override ThingTypeCheck<T> getVerifier(); @Override boolean hasSizeLimit(); @Override int getSizeLimit(); @Override int setSizeLimit(int limit); @Override boolean add(T o); @Override boolean offer(T o); @Override int size(); @Override boolean isEmpty(); @Override boolean contains(Object o); @Override Iterator<T> iterator(); @Override T[] toArray(); @Override T[] toArray(T[] a); @Override boolean remove(Object o); @Override boolean containsAll(Collection c); @Override boolean addAll(Collection c); @Override boolean removeAll(Collection c); @Override boolean retainAll(Collection c); @Override void clear(); @Override boolean equals(Object obj); @Override int hashCode();  }
@Test @Covers("public Collection<T> findSimilar(ThingTypeCheck<T>)") public void testFindSimilar() { ThingTypeCheck<Integer> judge = new SimpleIntegerCheck(1, 20); SimpleContainer<Integer> instance = new SimpleContainer<>(); instance.add(0); instance.add(1); instance.add(20); instance.add(21); instance.add(42); Collection<Integer> expResult = new ArrayList<>(); expResult.add(1); expResult.add(20); Collection result = instance.findSimilar(judge); assertEquals(expResult, result); }