如何正确验证 ZIO Test 中的计划调用

How to correctly verify scheduled invocations in ZIO Test

我是 ZIO 和 ZIO 测试的新手,我想测试我在 ZIO v1.0.0RC17 下编写的调度服务:

服务:

import zio.{RIO, Schedule}
import zio.clock.Clock
import zio.duration._

trait ModuleA {
  def moduleA: ModuleA.Service
}

object ModuleA {
  trait Service {
    def schedule(arg: Int): RIO[Clock, Unit]
  }
}

trait ModuleALive extends ModuleA {

  def moduleB: ModuleB.Service

  override def moduleA: ModuleA.Service = new ModuleA.Service {
    override def schedule(arg: Int): RIO[Clock, Unit] = {
      moduleB.run(arg).repeat(Schedule.spaced(1 day)).map(_ => ())
    }
  }
}

trait ModuleB {
  def moduleB: ModuleB.Service
}

object ModuleB {
  trait Service {
    def run(arg: Int): RIO[Clock, Unit]
  }
}

ModuleA 的服务基本上应该 运行 每天一次 ModuleB 的服务方法,并将参数输入 ModuleA.Service.run。

我想写的测试:

import java.util.concurrent.atomic.AtomicInteger

import zio.clock.Clock
import zio.duration._
import zio.test.environment.TestClock
import zio.test.{DefaultRunnableSpec, assertCompletes, suite, testM}
import zio.{RIO, Task, ZIO}

object ExampleSpec extends DefaultRunnableSpec(ExampleSuite.suite1)

object ExampleSuite {

  val counter: AtomicInteger = new AtomicInteger(0)

  trait ModuleBTest extends ModuleB {
    override def moduleB: ModuleB.Service = new ModuleB.Service {
      override def run(arg: Int): RIO[Clock, Unit] = ZIO.effectTotal(counter.incrementAndGet())
    }
  }

  object ModuleATest extends ModuleALive with ModuleBTest

  def verifyExpectedInvocationCount(expectedInvocationCount: Int): Task[Unit] = {
    val actualInvocations = counter.get()
    if (counter.get() == expectedInvocationCount)
      ZIO.succeed(())
    else
      throw new Exception(s"expected invocation count: $expectedInvocationCount but was $actualInvocations")
  }

  val suite1 = suite("a")(
    testM("a should correctly schedule b") {
      for {
        _ <- ModuleATest.moduleA.schedule(42).fork
        _ <- TestClock.adjust(12 hours)
        _ <- verifyExpectedInvocationCount(1)
        _ <- TestClock.adjust(12 hours)
        _ <- verifyExpectedInvocationCount(2)
      } yield assertCompletes
    }
  )
}

我使用计数器简化了测试,实际上我想使用 mockito 来验证调用计数以及正确的参数。但是,此测试不起作用。据我了解,这是因为 https://zio.dev/docs/howto/howto_test_effects#testing-clock.

中描述的时序开销引入了竞争条件

现在,有一些示例说明如何使用 Promise 来解决这个问题。我尝试用这样的承诺替换计数器:

import java.util.concurrent.atomic.AtomicInteger

import zio.test.{DefaultRunnableSpec, assertCompletes, suite, testM}
import zio.{Promise, Task, UIO, ZIO}

object ExampleSpec extends DefaultRunnableSpec(ExampleSuite.suite1)

object ExampleSuite {

  val counter: AtomicInteger = new AtomicInteger(0)
  var promise: UIO[Promise[Unit, Int]] = Promise.make[Unit, Int]

  trait ModuleBTest extends ModuleB {
    override def moduleB: ModuleB.Service = new ModuleB.Service {
      override def run(arg: Int) = promise.map(_.succeed(counter.incrementAndGet))
    }
  }

  object ModuleATest extends ModuleALive with ModuleBTest

  def verifyExpectedInvocationCount(expectedInvocationCount: Int, actualInvocations: Int): Task[Unit] = {
    if (actualInvocations == expectedInvocationCount)
      ZIO.succeed(())
    else
      throw new Exception(s"expected invocation count: $expectedInvocationCount but was $actualInvocations")
  }

  val suite1 = suite("a")(
    testM("a should correctly schedule b") {
      for {
        _ <- ModuleATest.moduleA.schedule(42).fork
        p <- promise
        actualInvocationCount <- p.await
        _ <- verifyExpectedInvocationCount(expectedInvocationCount = 1, actualInvocationCount)
      } yield assertCompletes
    }
  )
}

使用这个,测试不会终止。但是,我很确定我错误地使用了承诺。

如何正确处理这个测试场景?

在你的例子中 promise 的类型是 UIO[Promise[Unit, Int]] 所以你每次都在创建一个新的承诺。因此,您的效果正在完成的承诺与您的测试正在等待的承诺不同,从而导致未终止。

要对此进行测试,您可以这样做:

import zio.clock.Clock
import zio.duration._
import zio.test.environment.TestClock
import zio.test.{ assertCompletes, suite, testM, DefaultRunnableSpec }
import zio._

object ExampleSpec extends DefaultRunnableSpec {

  trait ModuleA {
    def moduleA: ModuleA.Service
  }

  object ModuleA {
    trait Service {
      def schedule(arg: Int): RIO[Clock, Unit]
    }
  }

  trait ModuleALive extends ModuleA {

    def moduleB: ModuleB.Service

    override def moduleA: ModuleA.Service = new ModuleA.Service {
      override def schedule(arg: Int): RIO[Clock, Unit] =
        moduleB.run(arg).repeat(Schedule.spaced(1.day)).map(_ => ())
    }
  }

  trait ModuleB {
    def moduleB: ModuleB.Service
  }

  object ModuleB {
    trait Service {
      def run(arg: Int): RIO[Clock, Unit]
    }
  }

  trait ModuleBTest extends ModuleB {
    val counter: Ref[Int]
    val invocations: Queue[Int]
    override def moduleB: ModuleB.Service = new ModuleB.Service {
      override def run(arg: Int): UIO[Unit] =
        counter.updateAndGet(_ + 1).flatMap(invocations.offer).unit
    }
  }

  object ModuleATest {
    def apply(ref: Ref[Int], queue: Queue[Int]): ModuleALive with ModuleBTest =
      new ModuleALive with ModuleBTest {
        val counter     = ref
        val invocations = queue
      }
  }

  def verifyExpectedInvocationCount(invocations: Queue[Int], expected: Int): Task[Unit] =
    invocations.take.flatMap { actual =>
      if (actual == expected)
        ZIO.succeed(())
      else
        ZIO.fail(new Exception(s"expected invocation count: $expected but was $actual"))
    }

  def spec = suite("a")(
    testM("a should correctly schedule b") {
      for {
        counter     <- Ref.make(0)
        invocations <- Queue.unbounded[Int]
        moduleATest = ModuleATest(counter, invocations)
        _           <- moduleATest.moduleA.schedule(42).fork
        _           <- TestClock.adjust(12.hours)
        _           <- verifyExpectedInvocationCount(invocations, 1)
        _           <- TestClock.adjust(12.hours)
        _           <- verifyExpectedInvocationCount(invocations, 2)
      } yield assertCompletes
    }
  )
}

由于我们要等待多个效果完成,所以我使用 Queue 来协调它们。其他一些注意事项:

  • 您可以使用 ZIO 测试中的断言替换 verifyExpectedInvocationsCount 方法以获得更好的错误报告。
  • 此示例使用旧环境编码。有了层,组合这些服务并交换其中一个的测试实现会容易得多。
  • 如果你想测试一个效果不会终止(例如,如果你没有等待足够的时间,另一个值永远不会放在队列中)你可以使用 TestAspect#nonTermination.