@Test public void testBasic() { assertTrue(_nbhs.isEmpty()); assertTrue(_nbhs.add("k1")); checkSizes(1); assertTrue(_nbhs.add("k2")); checkSizes(2); assertFalse(_nbhs.add("k1")); assertFalse(_nbhs.add("k2")); checkSizes(2); assertThat(_nbhs.remove("k1"), is(true)); checkSizes(1); assertThat(_nbhs.remove("k1"), is(false)); assertTrue(_nbhs.remove("k2")); checkSizes(0); assertFalse(_nbhs.remove("k2")); assertFalse(_nbhs.remove("k3")); assertTrue(_nbhs.isEmpty()); }