Derivation of the org.scalacheck.Arbitrary for case classes which was generated by the scalapb

ScalaPbArbitrary.scala

// libraryDependencies += "com.github.alexarchambault" %% "scalacheck-shapeless_1.14" % "1.2.0"
// libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.0"
// libraryDependencies += "com.thesamet.scalapb" %% "scalapb-runtime" % "0.8.4"

import org.scalacheck.{ Arbitrary, Gen, ScalacheckShapeless }
import scalapb.{ GeneratedEnum, GeneratedEnumCompanion, TypeMapper }

/**
  * Derives `or.scalacheck.Arbitrary` for generated by `scalapb` classes.
  *
  * @example
  * {{{
  * // Example.proto
  * syntax = "proto3";
  *
  * package scalacheck.scalapb.example;
  *
  * message Example {
  *     enum Variants {
  *         A = 0;
  *         B = 1;
  *     }
  *     int64 id = 1;
  *     Variants vars = 3;
  * }
  *
  * // scala
  * import ScalaPbArbitrary._
  * println(Arbitrary.arbitrary[Example].sample)
  *
  * // output
  * Some(Example(5387,B))
  * }}}
  */
trait ScalaPbArbitrary extends ScalacheckShapeless {
  implicit def arbitraryNewtype[A, B](implicit typeMapper: TypeMapper[A, B], arb: Arbitrary[A]): Arbitrary[B] =
    Arbitrary(arb.arbitrary.map(typeMapper.toCustom))

  implicit def arbitraryEnum[T <: GeneratedEnum](implicit companion: GeneratedEnumCompanion[T]): Arbitrary[T] =
    Arbitrary(Gen.oneOf(companion.values))
}

object ScalaPbArbitrary extends ScalaPbArbitrary