scala: can't import object from root scope

Question

I Have the following code: (src/main/scala/coins/coins.scala)

object Main extends App { 

  def countChange(money: Int, coins: List[Int]): Int = {
  [...]

And I'm trying to reference it from a test like this: (src/test/scala/coins/CoinsSuite.scala)

package coins

import org.scalatest.FunSuite

class CoinsSuite extends FunSuite {

  import Main.countChange
  test("only onw way to pay $0") {
  [...]

And I get the following error:

not found: value Main [error] import Main.countChange

But on the other hand, from an sbt console it works fine

If I declare any package in the main file, like

package x

object Main extends App { 
  Console.println("Hello World!")

Then I can correcly issue import x.Main.countChange

Is there limitation on root package or on singleton objects visibility that I'm not aware of?

-- added

just to complete the answer, a couple of useful links at SO

https://stackoverflow.com/a/2030159/47633

https://stackoverflow.com/a/9822212/47633

https://stackoverflow.com/a/9822227/47633

Answer 1

Java (and Scala according to the same convention) is grumpy about importing things in the unnamed package, which is not the same thing as the root package. Put Main into a package.

See Why is my object not a member of package <root> if it's in a separate source file?