How to do unit testing with sbt

Question
1

I have a file : ./src/main/scala/alain/main.scala :


package alain

import scala.Array
import scala.annotation.newMain
import fansi.Str
import fansi.Color.*

object myFunctions:
  def mySum(x:Int,y:Int):Int ={
    return x+y
  }

object MyTest:
  private class sumTest:
    def testMySum():Unit=
      if myFunctions.mySum(1, 2) == 5 then
        println("OK")
      else
        println("Error")


  @main
  private def main(args: String*): Int = {
    val fansiStr: fansi.Str = fansi.Color.Red("Hello World")
    println(fansiStr)
    (new sumTest).testMySum()
    0
  }

But i have totally no clue how to do unit testing.
Which libraries do i use ?
What do i put in build.sbt ?
Where do i put my code , in a separate file in ./src/test/ or not ?
What do i import there ?
Which sbt command do i run to test ?

2

As is typical for Scala, there are many potential test libraries you could use. But the default is generally ScalaTest, which is extremely thorough and pretty well-documented.

3

It remains very unclear to me, following questions remained unanswered,
What do i put in build.sbt ?
Where do i put my code , in a separate file in ./src/test/ or not ?
What do i import there ?
Which sbt command do i run to test ?

(with F# it’s a piece of cake)

4

A good page for getting basic familiarity with sbt is sbt Reference Manual — sbt by example

This project template could be useful:

sbt new scala/scalatest-example.g8 will use the template to make a sample project with a build.sbt that adds the ScalaTest dependency and example tests in src/test, including imports.

You might also consider using scala-cli instead of sbt; the learning curve is less steep. sbt really shines for large, sophisticated builds. Most smaller projects can get by just fine with scala-cli.

1 Like
5

Check out this doc page if you are interested in scala-cli and unit testing:

Note that from Scala >=3.5.0 you can write scala test . instead of scala-cli test . and you don’t need to install scala-cli if you have scala.

1 Like
6

This seemed to be very helpfull. Because i have a working example to start with.

I found out i didn’t needed any imports.
Just a class in test directory which extends org.scalatest.funsuite.AnyFunSuite.
The command to run was “sbt test”

Easy as a piece of cake. But without the example i would never figured it out of the documentation.

1 Like