使用嵌套的forAll在ScalaCheck中生成的对象之间共享元素

Sharing elements between generated objects in ScalaCheck using nested forAll

最近开始使用 Scala 编码，我尝试编写一些基于属性的测试用例。在这里，我试图生成模拟我正在测试的系统的原始数据。目标是首先生成基本元素(ctrl 和 idz)，然后使用这些值生成两个类(A1 和 B1)，最后检查它们的属性。我首先尝试了以下 -

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}

在终端中运行 sbt test 给了我以下 -

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}

现在很容易看出为什么第二个属性失败了。因为每次我产生 A1 和 B1 我都会为 id 而不是为 ctrl 产生不同的值，因为它是一个常数。以下是我的第二种方法，其中，我创建嵌套 for-yield 来尝试实现我的目标 -

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}

在第二种方法中运行 sbt test 告诉我所有测试都通过了。

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}

有没有更好/替代的方法来重现我想要的结果？嵌套 forAll 对我来说似乎相当笨拙。如果我的依赖图中有 R -> S -> ... V -> W 用于共享元素的对象，那么我将不得不创建尽可能多的嵌套 forAll.

我将在 Scalacheck 中给出答案。我知道 Scalatest 很受欢迎，但我发现将其包含在有关 Scalacheck 的问题中会分散注意力，尤其是当没有理由没有理由无法编写示例时。

您似乎想测试 A 和 B，但它们共享信息。表示该依赖关系的一种方法是您编写的 Popo 类。它既包含共享信息，也包含 A 和 B 的生成值。另一种选择是在类中生成 A 和 B 之间的共享值。

最简单的解决方案是成对生成 A 和 B(两个元组)。

不幸的是，有一些技巧可以让它发挥作用。您需要在 forAll 属性中使用 case 关键字。您不能为 Arbitrary 元组的 implicit 值提供证据，因此您必须在 forAll.

中明确指定元组的生成器

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}

关于您关于让对象共享信息的更广泛的问题，您可以通过编写带有函数参数的生成器来表示它。但是，它仍然需要嵌套的 forAll 生成器。

import org.scalatest._

import prop._

import scala.collection.immutable._

import org.scalacheck.{Gen, Arbitrary}



caseclass A(

  controller: String,

  id: Double,

  x: Double

)



caseclass B(

  controller: String,

  id: Double,

  y: Double

)



object BaseGenerators {

  val ctrl = Gen.const("ABC")

  val idz = Arbitrary.arbitrary[Double]

}



trait Generators {

  val obj = BaseGenerators



  val A1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    x <- Arbitrary.arbitrary[Double]

  } yield A(controller, id, x)



  val B1 = for {

    controller <- obj.ctrl

    id <- obj.idz

    y <- Arbitrary.arbitrary[Double]

  } yield B(controller, id, y)



}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.controller should be (b.controller)

    }

  }



  property("IDs are equal") {

    forAll(A1, B1) {

      (a:A,b:B) => 

        a.id should be (b.id)

    }

  }



}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal *** FAILED ***

[info]  TestFailedException was thrown during property evaluation.

[info]   Message: 1.1794559135007427E-271 was not equal to 7.871712821709093E212

[info]   Location: (testnew.scala:52)

[info]   Occurred when passed generated values (

[info]    arg0 = A(ABC,1.1794559135007427E-271,-1.6982696700585273E-23),

[info]    arg1 = B(ABC,7.871712821709093E212,-8.820696498155311E234)

[info]   )

caseclass Popo(

  controller: String,

  id: Double,

  someA: Gen[A],

  someB: Gen[B]

)



trait Generators {

  val obj = for {

    ctrl <- Gen.alphaStr

    idz <- Arbitrary.arbitrary[Double]

    val someA = for {

      x <- Arbitrary.arbitrary[Double]

    } yield A(ctrl, idz, someA)

    val someB = for {

      y <- Arbitrary.arbitrary[Double]

    } yield B(ctrl, idz, y)

  } yield Popo(ctrl, idz, x, someB)

}



class Something extends PropSpec with PropertyChecks with Matchers with Generators{



  property("Controllers are equal") {

    forAll(obj) {

      (x: Popo) => 

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.controller should be (b.controller)

      }

    }

  }



  property("IDs are equal") {

    forAll(obj) {

      (x: Popo) =>

      forAll(x.someA, x.someB) {

        (a:A,b:B) => 

          a.id should be (b.id)

      }

    }

  }

}

[info] Something:

[info] - Controllers are equal

[info] - IDs are equal

[info] ScalaTest

[info] Run completed in 335 milliseconds.

[info] Total number of tests run: 2

[info] Suites: completed 1, aborted 0

[info] Tests: succeeded 2, failed 0, canceled 0, ignored 0, pending 0

[info] All tests passed.
import org.scalacheck.Gen

import org.scalacheck.Arbitrary

import org.scalacheck.Prop

import org.scalacheck.Prop.AnyOperators

import org.scalacheck.Properties



caseclass A(

 controller: String,

 id: Double,

 x: Double

)



caseclass B(

 controller: String,

 id: Double,

 y: Double

)



object BaseGenerators {

 val ctrl = Gen.const("ABC")

 val idz = Arbitrary.arbitrary[Double]

}



object Generators {

 val obj = BaseGenerators



 val genAB: Gen[(A,B)] = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

  y <- Arbitrary.arbitrary[Double]

  val a = A(controller, id, x)

  val b = B(controller, id, y)

 } yield (a, b)                     // !

}



class Something extends Properties("Something") {



 property("Controllers and IDs are equal") = {

  Prop.forAll(Generators.genAB) { case (a: A, b: B) => // !

   a.controller ?= b.controller && a.id ?= b.id

  }

 }

}

object Generators {

 val obj = BaseGenerators



 val genA = for {

  controller <- obj.ctrl

  id <- obj.idz

  x <- Arbitrary.arbitrary[Double]

 } yield A(controller, id, x)



 def genB(a: A) = for {                 // !

  y <- Arbitrary.arbitrary[Double]

 } yield B(a.controller, a.id, y)

}



class Something extends Properties("Something") {



 implicitval arbA: Arbitrary[A] = Arbitrary {

  Generators.genA

 }



 property("Controllers and IDs are equal") = {

  Prop.forAll { a: A =>                // !

   Prop.forAll(Generators.genB(a)) { b: B =>     // !

    (a.controller ?= b.controller) && (a.id ?= b.id)

   }

  }

 }

}