JSON test file from Scalacheck Arbitrary/Circe Encoder

generate.scala

  def streamGen[A](gen: Gen[A]): Stream[IO, A] = Stream.repeatEval(IO(gen.sample)).flatMap(Stream.fromOption(_))

  def generateTestFile[A : Arbitrary : Encoder](file: fs2.io.file.Path, items: Long): IO[Unit] = {
    val values = streamGen(Arbitrary.arbitrary[A])
    val jsons = values.map(Encoder[A].apply).take(items)
    val lines = Stream("[\n") ++ jsons.map(_.toString()).intersperse(",\n") ++ Stream("]") 

    lines
      .through(text.utf8.encode)
      .through(Files[IO].writeAll(file))
      .compile
      .drain
  }