/**
  * @test
  * @depends I_can_get_property_easily
  * @param AbstractDerivedProperty $derivedProperty
  */
 public function I_can_add_and_remove_value_from_property(AbstractDerivedProperty $derivedProperty)
 {
     $increased = $derivedProperty->add(123);
     self::assertNotEquals($derivedProperty, $increased);
     self::assertSame($derivedProperty->getValue() + 123, $increased->getValue());
     $decreased = $derivedProperty->sub(456);
     self::assertNotEquals($derivedProperty, $decreased);
     self::assertSame($derivedProperty->getValue() - 456, $decreased->getValue());
 }