Scala Create an iterator using a Stream over 2 "aligned" files

gistfile1.scala

  test("Detect barcodes in forward and reverse reads in Fastq format") {
    val readerR1 = new FastqReader(new java.io.File(getClass.getResource("/R1.fastq.gz").getPath))
    val readerR2 = new FastqReader(new java.io.File(getClass.getResource("/R2.fastq.gz").getPath))
    var list = List[String]()
   
    case class Reads( r1: FastqRecord, r2: FastqRecord)
    
    val stream: Stream[Reads]= {
      def reads(readerR1: FastqReader, readerR2: FastqReader): Stream[Reads] = {
        readerR1.hasNext() && readerR2.hasNext()  match {
          case true => Reads(readerR1.next(), readerR2.next()) #:: reads(readerR1, readerR2)
          case _ => Stream.empty
        }
      }
     reads(readerR1, readerR2)
    }
    
    for ( read <- stream) {
      println(read.r1.getReadHeader)
      println(read.r2.getReadHeader)
      //list = list:+ TcrIndex.detect(barcode, read.r1, read.r2)
    }
    assert(list == List("1A1","1B4","" ,"" ,"" ,"" ,"" ,"" ,"" ,"" ,""))
  }