根据另一个 Gen 定义 ScalaCheck 生成器

Question

如何定义一个生成器来为给定 Block 的 fields 生成随机数据。以下是脚手架代码。我需要有关替换 ??? 的表达式的帮助。此表达式应生成 Seq[Field]，但 Field 应使用定义的 genField 函数生成。

def blockGen(b: Block): Gen[Block] = for {
    id <- b.blockId //Use the same blockId as b
    fields <- ??? //Get the type from each field and call genField
} yield Block(id, fields)

ADT

trait Data {}

trait Field extends Data {
  val name: String
  val value: String
}

case class StringField(name: String, value: String) extends Field
case class NumberField(name: String, value: String) extends Field
case class Block(blockId: Field, fields: Seq[Field]) extends Data

发电机

def fieldGen(fieldType: Field): Gen[Field] = {
  for {
    f <-
    fieldType match {
      case _: NumberField => numGen
      case _: StringField => strGen
    }
  } yield f
}

val strGen: Gen[StringField] = for {
  name <- Gen.identifier
  value <- Gen.alphaStr
} yield StringField(name, value)

val numGen: Gen[NumberField] = for {
  name <- Gen.identifier
  value <- Gen.numStr
} yield NumberField(name, value)

示例块：myBlock

val cx = new StringField("blockId", "CX")
val seg = StringField("segmentation", "ABC")
val ver = NumberField("version", "1.0")

val myBlock = Block(cx, Seq(seg, ver))

Answer 1

我相信你要找的是Gen.sequence。

此外，id 不需要来自生成器，因为您所做的只是直接使用特定值。

def blockGen(b: Block): Gen[Block] =
  for {
    fields <- Gen.sequence[Seq[Field], Field](b.fields.map(fieldGen))
  } yield Block(b.blockId, fields)

顺便说一下，Gen.sequence 与 Future.sequence and sequence in Haskell 非常相似。

根据另一个 Gen 定义 ScalaCheck 生成器

Defining a ScalaCheck generator in terms of another Gen

scala

scalacheck