public IntValue increment(int increment) {
    this.value += increment;
    this.set = true;
    return this;
  }
@Test
  public void increment_IntValue_increments_by_the_value_of_the_arg() {
    IntValue source = new IntValue().increment(10);
    IntValue target = new IntValue().increment(source);

    verifySetValue(target, 10);
  }