How to test capture checking?

Question
1

Is it possible to test capture checking programmatically, using ScalaTest or something similar?

class CCSpec extends AnyFlatSpec with Matchers {
  "Capture checking" should "fails compilation" in {
    val errors = typeCheckErrors("""
      import language.experimental.captureChecking
      import java.io.{FileInputStream, InputStream}

      def withFile[T](name: String)(op: InputStream^ => T): T =
        val f = new FileInputStream(name)
        try op(f)
        finally f.close()

      withFile("data.txt"): in =>
        in.read()
    """)
    errors shouldBe empty
  }
}

The code above fails, but the error doesn’t indicate that the resource was leaked, but the following:Capture checking
- should fails compilation *** FAILED *** (11 milliseconds)
  List(Error("this language import is only allowed at the toplevel", "      import language.experimental.captureChecking", 35, Parser)) was not empty (CCSpec.scala:74)

If we remove the import language.experimental.captureChecking from the code in the string and move it to the top of the CCSpec.scala file, it will be ignored by the compiler.