Running test case in Scala gives "discarded non-Unit value"

Question

I am newbie to scala

My sbt version is : 0.13.17

I am trying to run the test case with the following code

class TestSpec extends WordSpec with Matchers with MockFactory with OneAppPerSuite {

  "it" should {
    "add 2 numbers" in new Testing() {
      val a = 2
      val b = 3
      val expected = 5
      val result: Int = add(2, 3)

      result shouldEqual expected
    }
  }

  trait Testing {

    def add(a: Int, b: Int): Int = {
      a + b
    }
  }
}

And i get the following error

discarded non-Unit value
 "add 2 numbers" in new Testing() {

In my build.sbt file i see this

"-Ywarn-value-discard", // Warn when non-Unit expression results are unused

I cant remove the above line and how do i make sure my test case executes.

I have gone through this link Suppress "discarded non-Unit value" warning. But not sure what needs to be done. Any help is highly appreciated

If this is just a warning, are your tests still running? Or is this actually stopping your tests from working? — James Whiteley, Feb 06 '19 at 14:31
@JamesWhiteley My tests are stopped. I get an Error not a warning — Avinash Reddy, Feb 06 '19 at 16:16

score 1 · Answer 1 · answered Feb 11 '19 at 12:03

I just tried something like ... And it works.

class Testclass extends  FlatSpec with Matchers  with TestTrait {
  it should "add two integers" in  {
      val a: Int =  2
      val b: Int =  3
      val result = add(a, b)
      result shouldEqual(5)
    }
}

trait TestTrait {
  def add(a: Int, b: Int):Int = {
     a + b
  }
}

score -1 · Answer 2 · answered Feb 06 '19 at 14:39

-1

This warning arises because the assigned values a and b are not used. Maybe you meant to write:

val result: Int = add(a, b)

answered Feb 06 '19 at 14:39

Serge Kireev

176
1
8

score -1 · Answer 3 · answered Apr 28 '20 at 15:10

-1

disable -Ywarn-value-discard in scalacOptions

answered Apr 28 '20 at 15:10

Abhishek Sengupta

2,938
1
28
35

Running test case in Scala gives "discarded non-Unit value"

3 Answers3