Test LazyList in scala-compat

build.sbt

ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / scalaVersion := "2.12.17"
ThisBuild / crossScalaVersions := Seq("2.12.17", "2.13.8")

lazy val root = (project in file("."))
  .settings(
    libraryDependencies += "org.scala-lang.modules" %% "scala-collection-compat" % "2.9.0"
  )

output

sbt +run
[info] welcome to sbt 1.8.0 (Oracle Corporation Java 11.0.2)
[info] loading settings for project global-plugins from plugins.sbt,sbt-updates.sbt ...
[info] loading global plugins from /Users/fede/.sbt/1.0/plugins
[info] loading project definition from /Users/fede/development/workspace/scala-2.12/project
[info] loading settings for project root from build.sbt ...
[info] set current project to root (in build file:/Users/fede/development/workspace/scala-2.12/)
[info] Setting Scala version to 2.12.17 on 1 projects.
[info] Reapplying settings...
[info] set current project to root (in build file:/Users/fede/development/workspace/scala-2.12/)
[info] compiling 1 Scala source to /Users/fede/development/workspace/scala-2.12/target/scala-2.12/classes ...
[info] running TestCollection
3 shouldBe 3
4 shouldBe 4
6 shouldBe 6
[success] Total time: 5 s, completed Apr 12, 2023, 10:02:53 AM
[info] Setting Scala version to 2.13.8 on 1 projects.
[info] Reapplying settings...
[info] set current project to root (in build file:/Users/fede/development/workspace/scala-2.12/)
[info] compiling 1 Scala source to /Users/fede/development/workspace/scala-2.12/target/scala-2.13/classes ...
[info] running TestCollection
3 shouldBe 3
4 shouldBe 4
6 shouldBe 6
[success] Total time: 4 s, completed Apr 12, 2023, 10:02:57 AM
[info] Reapplying settings...
[info] set current project to root (in build file:/Users/fede/development/workspace/scala-2.12/)

TestCollection.scala

import scala.collection.compat._

object TestCollection extends App {

  var rec = 0

  def llRange(lo: Int, hi: Int): immutable.LazyList[Int] = {
    rec = rec + 1
    if (lo >= hi) immutable.LazyList.empty
    else immutable.LazyList.cons(lo, llRange(lo + 1, hi))
  }

  llRange(1, 10).take(3).toList
  println(s"$rec shouldBe 3")
  llRange(1, 10).take(1).toList
  println(s"$rec shouldBe 4")
  llRange(1, 10).take(2).toList
  println(s"$rec shouldBe 6")

}