TestHashSet<Entry<String>> entrySet = new TestHashSet<>();
    when((Comparator<Comparable<String>>) toCopy.comparator())
        .thenReturn(Ordering.<Comparable<String>>natural());
    when(toCopy.entrySet()).thenReturn(entrySet);
    ImmutableSortedMultiset<String> unused = ImmutableSortedMultiset.copyOfSorted(toCopy);
    assertTrue(entrySet.toArrayCalled);
  }