@Test public void isProperSubsetOf() { MutableSet<String> set = MultiReaderUnifiedSet.newSetWith("1", "2", "3", "4").asReadUntouchable(); Assert.assertTrue(set.isProperSubsetOf(UnifiedSet.newSetWith("1", "2", "3", "4", "5"))); Assert.assertFalse(set.isProperSubsetOf(set)); }