@Test
  public void exchangeRateService() {

    ExchangeRateService service = new ExchangeRateService();
    assertEquals(wechselkursEuro2Chf, service.getRate(euro, chf), 0.00001);
    assertEquals(wechselkursChf2Euro, service.getRate(chf, euro), 0.00001);
    assertEquals(2, service.getRate(dollar, euro), 0.00001);
    assertEquals(1 / 2, service.getRate(euro, dollar), 0.00001);
  }
  ///////////////////////////////////////////
  //   Exercise: class that adds Euro and CHF
  //
  //   Wechselkurs
  //   W�hrung
  //   Zielw�hrung ber�cksichtigen!
  //   done Summands are changeable
  //   Wie kommt der Wechselkurs in die Methode?
  //
  //
  @Test
  public void addCurrency() {

    Adder adder = new Adder();
    ExchangeRateService service = new ExchangeRateService();

    assertEquals(5 + 10 * service.getRate(chf, euro), adder.add(5, euro, 10, chf, euro), 0.00001);
    assertEquals(7 + 10 * service.getRate(chf, euro), adder.add(7, euro, 10, chf, euro), 0.00001);
    assertEquals(7 + 10 * service.getRate(chf, euro), adder.add(10, chf, 7, euro, euro), 0.00001);
    assertEquals(
        (7 + 10 * service.getRate(chf, euro)) * service.getRate(euro, chf),
        adder.add(10, chf, 7, euro, chf),
        0.00001);
    assertEquals(5 + 10, adder.add(5, euro, 10, euro, euro), 0.00001);
    assertEquals(5 + 10, adder.add(5, chf, 10, chf, chf), 0.00001);
    assertEquals(
        5 + 10 * service.getRate(dollar, euro), adder.add(5, euro, 10, dollar, euro), 0.00001);
  }