scala/scalatest bug reproduction for https://github.com/scala/bug/issues/12441 and https://github.com/scalatest/scalatest/issues/2056

bug.scala

package bug.example

import org.scalatest.funsuite.AnyFunSuite

class SetSuite extends AnyFunSuite {
  test("An empty Set should have size 0") {
    // Option.empty[String].contains(1234)  // WARNS
    assert(Set.empty.size == 0)
  }

  test("Invoking head on an empty Set should produce NoSuchElementException") {
    assertThrows[NoSuchElementException] {
      // Option.empty[String].contains(1234) // WARNS
      Set.empty.head
    }
  }
}

import org.scalatest.flatspec.AnyFlatSpec

class SetFlatSpec extends AnyFlatSpec {

  "An empty Set" should "have size 0" in {
    Option.empty[String].contains(1234)
    assert(Set.empty.size == 0)
  }

  it should "produce NoSuchElementException when head is invoked" in {
    assertThrows[NoSuchElementException] {
      Option.empty[String].contains(1234)
      Set.empty.head
    }
  }
}

import org.scalatest.funspec.AnyFunSpec

class SetFunSpec extends AnyFunSpec {

  describe("A Set") {
    describe("when empty") {
      it("should have size 0") {
        // Option.empty[String].contains(1234) // WARNS
        assert(Set.empty.size == 0)
      }

      it("should produce NoSuchElementException when head is invoked") {
        assertThrows[NoSuchElementException] {
          // Option.empty[String].contains(1234) // WARNS
          Set.empty.head
        }
      }
    }
  }
}

import org.scalatest.wordspec.AnyWordSpec

class SetWordSpec extends AnyWordSpec {

  "A Set" when {
    "empty" should {
      "have size 0" in {
        Option.empty[String].contains(1234)
        assert(Set.empty.size == 0)
      }

      "produce NoSuchElementException when head is invoked" in {
        assertThrows[NoSuchElementException] {
          Option.empty[String].contains(1234)
          Set.empty.head
        }
      }
    }
  }
}

import org.scalatest.freespec.AnyFreeSpec

class SetFreeSpec extends AnyFreeSpec {

  "A Set" - {
    "when empty" - {
      "should have size 0" in {
        Option.empty[String].contains(1234)
        assert(Set.empty.size == 0)
      }

      "should produce NoSuchElementException when head is invoked" in {
        assertThrows[NoSuchElementException] {
          Option.empty[String].contains(1234)
          Set.empty.head
        }
      }
    }
  }
}

import org.scalatest._
import org.scalatest.propspec._
import matchers._
import prop._
import scala.collection.immutable._

class SetPropSpec extends AnyPropSpec with TableDrivenPropertyChecks with should.Matchers {

  val examples =
    Table[AbstractSet[Int]](
      "set",
      BitSet.empty,
      HashSet.empty[Int],
      TreeSet.empty[Int]
    )

  property("an empty Set should have size 0") {
    forAll(examples) { set =>
      // Option.empty[String].contains(1234) // WARNS
      set.size should be (0)
    }
  }

  property("invoking head on an empty set should produce NoSuchElementException") {
    forAll(examples) { set =>
      a [NoSuchElementException] should be thrownBy {
        Option.empty[String].contains(1234)
        set.head
      }
    }
  }
}