Created
December 8, 2021 11:27
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RichModel2
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public class OrderTest { | |
/** | |
* This test shows that a rich model gurantees that it is in a legal state | |
* at any time. | |
*/ | |
@Test | |
public void richDomainModelMustEnsureToBeConsistentAtAnyTime() { | |
Order order = new Order(); | |
BigDecimal total = order.getTotal(); | |
/* | |
* A new order has no items and therefore the total must be zero. | |
*/ | |
assertEquals(BigDecimal.ZERO, total); | |
OrderItem aGoodBook = new OrderItem(new BigDecimal("30"), 5, | |
"Domain-Driven"); | |
List<OrderItem> items = order.getItems(); | |
try { | |
items.add(aGoodBook); | |
} catch (UnsupportedOperationException e) { | |
/* | |
* We CAN NOT BREAK ENCAPSULATION, because the order object will not | |
* expose it's internal state to clients. It takes care about it's | |
* state and ensures that it is in a legal state at any time. | |
*/ | |
} | |
/* | |
* We have to use the object's mutator method | |
*/ | |
order.addItem(aGoodBook); | |
/* | |
* After we added an OrderItem. The object is still in a legal state. | |
*/ | |
BigDecimal totalAfterItemAdd = order.getTotal(); | |
BigDecimal expectedTotal = new BigDecimal("150"); | |
assertEquals(expectedTotal, totalAfterItemAdd); | |
} | |
} |
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