ScalaMock 和蛋糕模式 - 为什么我的存根没有被调用？

Question

我有一个使用 Cake 模式的 Scala 应用程序：

trait RepositoryComponent {
  def repository: Repository

  trait Repository {
    def shouldSave(record: GenericRecord): Boolean
    def findRecord(keys: Array[String]): Long
    def insertRecord(record: GenericRecord)
    def updateRecord(keys: Array[String], record: GenericRecord)
    def cleanUp()
  }
}

trait DbRepositoryComponent extends RepositoryComponent with Logged {
  val connection: Connection
  val subscription: Subscription
  val schema: Schema

  def repository = new DbRepository(connection, subscription, schema)

  class DbRepository(connection: Connection, subscription: Subscription, schema: Schema) extends Repository {
    ...
  }

trait ConsumerComponent {
  def consumer: Consumer

  trait Consumer {
    def write(keys: Array[String], record: GenericRecord)
    def close()
  }
}

trait DbReplicatorComponent extends ConsumerComponent with Logged {
  this: RepositoryComponent =>

  def consumer = new DatabaseReplicator()

  class DatabaseReplicator extends Consumer {
    ...
  }

当我天真地开始测试consumer.write的实现时，我尝试了这样的事情（使用ScalaMock）：

class DbReplicatorComponentTests extends FunSuite with MockFactory {

  private val schema = new Schema.Parser().parse(getClass.getResourceAsStream("/AuditRecord.avsc"))
  private val record = new GenericRecordBuilder(schema)
    .set("id1", 123)
    .set("id2", "foo")
    .set("text", "blergh")
    .set("audit_fg", "I")
    .set("audit_ts", 1498770000L)
    .build()

  test("A record should be inserted if the audit flag is 'I' and no existing record is found") {
    val replicator = new DbReplicatorComponent with RepositoryComponent {
      override def repository: Repository = stub[Repository]
    }

    (replicator.repository.shouldSave _).when(record).returns(true)
    (replicator.repository.findRecord _).when(Array("123", "foo")).returns(0L)

    replicator.consumer.write(Array("123", "foo"), record)

    (replicator.repository.insertRecord _).verify(record)
  }
}

测试失败，因为我没有对实际实现进行存根：

Unsatisfied expectation:

Expected:
inAnyOrder {
  <stub-1> Repository.shouldSave({"id1": 123, "id2": "foo", "text": "blergh", "audit_fg": "I", "audit_ts": 1498770000}) any number of times (never called)
  <stub-2> Repository.findRecord([Ljava.lang.String;@4b8ee4de) any number of times (never called)
  <stub-4> Repository.insertRecord({"id1": 123, "id2": "foo", "text": "blergh", "audit_fg": "I", "audit_ts": 1498770000}) once (never called - UNSATISFIED)
}

Actual:
  <stub-3> Repository.shouldSave({"id1": 123, "id2": "foo", "text": "blergh", "audit_fg": "I", "audit_ts": 1498770000})
ScalaTestFailureLocation: com.generalmills.datalake.sql.DbReplicatorComponentTests at (DbReplicatorComponentTests.scala:12)
org.scalatest.exceptions.TestFailedException: Unsatisfied expectation:

这个问题凸显了我真的不理解 Scala 的事实。我不知道 stub-3 从何而来。我已经根据 damirv 在 this question 中的回答成功地修改了我的测试，但我希望这里有一些见解可以帮助我更好地理解 为什么我实际上并没有嘲笑我认为我对测试上面?

顺便说一下，我是从 C# 背景来到 Scala 的。

更新：根据下面的答案，这个有效：

test("A record should be inserted if the audit flag is 'I' and no existing record is found") {
    val replicator = new DbReplicatorComponent with RepositoryComponent {
      val _repo = stub[Repository]
      override def repository: Repository = {
        _repo
      }
    }

    (replicator.repository.shouldSave _).when(record).returns(true)
    (replicator.repository.findRecord _).when(Array("123", "foo")).returns(0L)

    replicator.consumer.write(Array("123", "foo"), record)

    (replicator.repository.insertRecord _).verify(record)
  }

Answer 1

def repository: Repository 这是一种每次调用时 return 都会创建一个新存根的方法。尝试将其设为 val 而不是 return 每个 invocation/access:

上的相同存根

test("A record should be inserted if the audit flag is 'I' and no existing record is found") {
  val replicator = new DbReplicatorComponent with RepositoryComponent {
    override val repository: Repository = stub[Repository]
  }
  // ...
}

此外，您正在使用数组作为参数类型。请注意 Scala 中的 Array("foo") != Array("foo")，因此我建议您在使用数组 (findRecord) 的 when 调用中使用 argThat 匹配器 - 参见此处：Unable to create stub with Array argument in ScalMock

或尝试谓词匹配，如下所述：http://scalamock.org/user-guide/matching/

ScalaMock 和蛋糕模式 - 为什么我的存根没有被调用？

ScalaMock and the Cake Pattern - Why is my stub not called?

unit-testing

scala

scalamock