ScalaTest：瞭解測試執行順序

Question

我很努力地理解爲什麼我的設置 - 拆卸過程不像我在ScalaTest中所期望的那樣工作。基本上，我的測試代碼如下：

class UserManagerTest extends FlatSpec with ManagerBehaviors[User, UserDAO] { 

    "An entity manager" should behave like allFindingManager(UserManager) 

    "An entity manager" should behave like countingManager(UserManager) 
} 


trait ManagerBehaviors[T <: IEntity, D <: AbstractDAO[T]] { 

this: FlatSpec => 

    private def withClearDB(entityManager: BasicManager[T, D], testFunction:() => Unit) = { 
    try { 
     clearDB(entityManager) 
     testFunction() 
    } finally { 
     clearDB(entityManager) 
    } 
    } 

    private def clearDB(manager: BasicManager[T, D]) = { 
    manager.all match { 
     case Some(entities) => for (entity <- entities) manager.remove(entity.getId) 
    } 
    } 

    def allFindingManager(manager: BasicManager[T, D]) { 
    withClearDB(manager, 
    () => it should "properly return all elements in the database for the entity" in { 

     // Add 10 entities to the database 
     for (i <- 1 to 10) manager.persist(manager.defaultEntity) 

     manager.all match { 
      case Some(entities) => assert(entities.length == 10) 
      case None => fail() 
     } 
     }) 
    } 

    def countingManager(manager: BasicManager[T, D]) { 
    withClearDB(manager, 
    () => it should "properly count the number of entities managed" in { 

     // Add 10 entities to the database 
     for (i <- 1 to 10) manager.persist(manager.defaultEntity) 

     assert(manager.count == 10) 
     }) 
    } 
} 

我想到的是下面的順序：

1. clearDB

2. allFindingManager

3. clearDB

4. clearDB

5. countingManager

6. clearDB

當單獨運行，測試按預期工作 - 數據庫是在啓動時被清除，留下空當測試結束。

但是，運行整個UserManagerTest類時，由於某種原因失敗，出現以下：

org.scalatest.exceptions.TestFailedException: 20 did not equal 10 

這樣做的原因是，不知何故，該測試被稱爲對方右後無間斷clearDB調用。我無能爲力，爲什麼會發生這種情況。

當使用調試器並在finally塊內放置斷點時，發現發生了什麼的可能線索：此塊確實運行了兩次，如預期的那樣，但是這發生在BEFORE（！）測試方法執行之前，這使得沒有任何意義：

1. clearDB

2. clearDB

3. clearDB

4. clearDB

5. allFindingManager

6. countingManager

誰能幫助我闡明這一些輕？

Answer 1

如果更改

def countingManager(manager: BasicManager[T, D]) { 
    withClearDB(manager, 
    () => it should "properly ..." in { 

     // Add 10 entities to the database 
     for (i <- 1 to 10) manager.persist(manager.defaultEntity) 

     assert(manager.count == 10) 
    }) 
} 

到

def countingManager(manager: BasicManager[T, D]) { 

    it should "properly ..." in withClearDB(manager, 
    () => { 
     // Add 10 entities to the database 
     for (i <- 1 to 10) manager.persist(manager.defaultEntity) 

     assert(manager.count == 10) 
    } 
) 

} 

，並同樣在其他功能，則執行順序將會像你期望的那樣。