PaymentUsingFactory.java

PaymentUsingFactory.java

  interface CreditCard {

    void charge(Double amount);

  }

  interface CreditCardFactory {

    CreditCard create(String customerId);
  }

  class VisaCreditCardFactory implements CreditCardFactory {
    
    @Override
    public CreditCard create(String customerId) {
      return new CreditCard() {
        @Override
        public void charge(Double amount) {
          try {
            URLConnection urlConnection = new URL("http://mybank.com/secureurl/bank").openConnection();

          } catch (IOException e) {
            e.printStackTrace();
          }
        }
      };
    }
  }

  class Payment {
    private final CreditCardFactory factory;
    
    public Payment(CreditCardFactory factory) {
      this.factory = factory;
    }

    void process(String customerId, Double amount) {
      CreditCard creditCard = factory.create(customerId);
      creditCard.charge(amount);
    }
  }

  class DummyCreditCard implements CreditCard {

    public Double chargedAmount;

    @Override
    public void charge(Double amount) {
      this.chargedAmount = amount;
    }
  }

  @Test
  public void creditCardIsChargedWhenPaymentIsProcessed() {
    final DummyCreditCard creditCard = new DummyCreditCard();
    Payment payment = new Payment(new CreditCardFactory() {
      @Override
      public CreditCard create(String customerId) {
        return creditCard;
      }
    });

    payment.process("george", 20d);

    assertThat(creditCard, wasChargedWith(20d));

  }

  private Matcher<DummyCreditCard> wasChargedWith(final Double expectedAmount) {
    return new TypeSafeMatcher<DummyCreditCard>() {
      @Override
      protected boolean matchesSafely(DummyCreditCard dummyCreditCard) {
        return expectedAmount.equals(dummyCreditCard.chargedAmount);
      }

      @Override
      public void describeTo(Description description) {
      }
    };
  }