Question

我是猫和函数式编程的新手，并且正在尝试测试EitherT之类的函数数据类型。有示例代码：

class Library[F[_]]() {
    def create(book: Book)(implicit M: Monad[F]): EitherT[F, BookAlreadyExistsError, Book] = ...
}

我想使用Spec2对其进行测试，但我不知道如何正确执行。尝试过类似的操作，但不起作用：

  val library = Library[IO]()

  test("create book") {

    val book = Book("Title 1", 2016, "author 1")
    (for (
      resultBook <- library.create(book)
    ) yield resultBook shouldEqual ???
    ).unsafeRunSync()

  }

我想要一个非常简单的断言，像这样：

   resultBook shouldEqual Right(Book("Title 1", 2016, "author 1"))
   // or
   resultBook shouldEqual Left(BookAlreadyExistsError)

Answer 1

specs2-cats提供了IOMatchers特征，它启用了以下语法

library.create(book).value must returnValue(Right(book))

其中

libraryDependencies += "org.specs2" %% "specs2-core" % "4.8.1" % Test,
libraryDependencies += "org.specs2" %% "specs2-cats" % "4.8.1" % Test,

这是一个可行的例子

import cats.data.EitherT
import cats.effect.IO
import org.specs2.mutable.Specification
import org.specs2.matcher.IOMatchers

class CatsSpec extends Specification with IOMatchers {
  case class Book(title: String, year: Int, author: String)
  def create(book: Book): EitherT[IO, String, Book] = EitherT(IO(Right(book).withLeft[String]))
  val book = Book("Title 1", 2016, "author 1")

  "specs2-cats dependency" should {
    "provide matcher for IO effect" in {
      create(book).value must returnValue(Right(book))
    }
  }
}

猫的匹配器EitherT和效果

1 个答案: