only method not working in Scala 3 Matchers (as List)

[yadavan88]

Hi,
I am trying to migrate a Scala 2 code to scala 3 that uses only matcher. It works fine in scala 2, but not in scala 3. Here is the scala 2 code that works:

val cities = List("Barcelona", "Hamburg")
val cities2 = List("Barcelona", "Hamburg")
cities ++ cities should contain only (cities2: _*) 

However, this was giving an error in scala 3 with the usage of vararg(: _*) that it is not supported. So I tried with removing the vararg. It compiles but test fails as there are more elements. Is this method only cant be used in Scala 3 anymore?

val cities = List("Barcelona", "Hamburg")
val cities2 = List("Barcelona", "Hamburg")
cities ++ cities should contain only cities2

EDIT:
if I use cities ++ cities should contain only ("Barcelona", "Hamburg") then it works. So there is some problem with the vararg in Scala 3. I tried * and : _*, but both didn't work.
However, it works fine when I tried with a simple method that takes vararg:

def test(list: String*) = { println(list) }
val list = List("a", "b")
test(list:_*)
test(list*)

Thanks in advance
Yadu

[cheeseng]

@yadavan88 Sorry we somehow didn't notice your message, yes I think Scala 3 explicitly says the syntax no longer works:

[error] -- Error: /home/cheeseng/git/artima/scalatest/dotty/scalatest-test/target/scala-3/src_managed/test/org/scalatest/ListShouldContainOnlySpec.scala:143:45 
[error] 143 |        cities should contain only (cities2: _*) 
[error]     |                                             ^
[error]     |        `_*` can be used only for last argument of method application.
[error]     |        It is no longer allowed in operands of infix operations.

I am not sure why we didn't have onlyElementsOf like allOf pairing with allElementsOf, @bvenners perhaps we should add that in?

For now perhaps the only workaround I can think of is:

(cities should contain).only(cities2: _*)