assertEquals(3, multiset.count(s2));

    multiset.remove(s1);
    assertEquals(1, multiset.count(s1));
    assertEquals(3, multiset.count(s2));
  }

  public void testLogicalKeyEquality_strongKeys() {
    testLogicalKeyEquality(STRONG);
  }

  public void testLogicalKeyEquality_weakKeys() {
    testLogicalKeyEquality(WEAK);
  }