Scala / specs2：找不到 AsExecution[ExecutionEnv => MatchResult[Future[AuthenticationResult]]] 类型的证据参数的隐式值

Question

我正在尝试将 Scala/Play 应用程序升级到Play 2.7 、 Scala 2.12.11 。

在升级 Play 和 Scala 之前，我进行了以下测试。

升级后出现如下编译错误：

Error: could not find implicit value for evidence parameter of type org.specs2.specification.core.AsExecution[org.specs2.concurrent.ExecutionEnv => org.specs2.matcher.MatchResult[scala.concurrent.Future[services.AuthenticationResult]]]

import org.specs2.concurrent.ExecutionEnv
import org.specs2.mutable.Specification

import scala.concurrent.duration._

class AuthenticationServiceSpec extends Specification {

  "The AuthenticationService" should {

    val service: AuthenticationService = new MyAuthenticationService

    "correctly authenticate Me" in { implicit ee: ExecutionEnv =>
      service.authenticateUser("myname", "mypassowrd") must beEqualTo (AuthenticationSuccessful).await(1, 200.millis)
    }

  }

}

为了尝试解决编译错误，我在 class 构造函数中添加了一个隐式参数（顺便说一句，之前它是如何工作的，没有隐式参数？）：

import org.specs2.concurrent.ExecutionEnv
import org.specs2.mutable.Specification

import scala.concurrent.duration._
import scala.concurrent.Future

import org.specs2.specification.core.AsExecution
import org.specs2.matcher.MatchResult    

class AuthenticationServiceSpec(implicit ee: AsExecution[ExecutionEnv => MatchResult[Future[AuthenticationResult]]]) extends Specification {

  "The AuthenticationService" should {

    val service: AuthenticationService = new MyAuthenticationService

    "correctly authenticate Me" in { implicit ee: ExecutionEnv =>
      service.authenticateUser("myname", "mypassowrd") must beEqualTo (AuthenticationSuccessful).await(1, 200.millis)
    }

  }

}

但是在运行时，当我运行测试时，我得到了错误：

Can't find a suitable constructor with 0 or 1 parameter for class org.specs2.specification.core.AsExecution

基于AsExecution的构造函数，这很有意义......

那我该如何解决这个问题呢？

Answer 1

这应该工作

class AuthenticationServiceSpec(implicit ee: ExecutionEnv) extends Specification {

  "The AuthenticationService" should {

    val service: AuthenticationService = new MyAuthenticationService

    "correctly authenticate Me" in {
      service.authenticateUser("myname", "mypassword") must beEqualTo (AuthenticationSuccessful).await(1, 200.millis)
    }

  }

}

ee: ExecutionEnv在构建时会直接注入到规范中。

这就是消息Can't find a suitable constructor with 0 or 1 parameter for class... 。 如果 specs2 有一个带 0 或 1 个参数的构造函数，则specs2尝试为规范递归构建 arguments。 ExecutionEnv就是这样一个参数， specs2能够自行构建。