assertThrows(IllegalArgumentException.class, () -> getMultiset().remove(e0(), -1));
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemoveUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> getMultiset().remove(e0(), 2));
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveZeroNoOp() {