Save scalacheck generated data as json on failure in scalatest

TestFailExample.scala

class TestFailExample extends FlatSpec with GeneratorDriverPropertyChecks
  it should "foo" in {
    val genData: Gen[T]
    IO(
      forAll(genData) {
        // test here
      }
    ).onError {
        case e: GeneratorDrivenPropertyCheckFailedException =>
          val data = e.args.head
            .asInstanceOf[Prop.Arg[T]]
            .arg
          val path = new File("test_fail_data.json").toPath
          fs2.Stream
            .emit(data.toJson.compactPrint)  // spray, but could be anything
            .covary[IO]
            .through(fs2.text.utf8Encode)
            .to(
              fs2.io.file.writeAll[IO](path)
            )
            .compile
            .drain
      }
      .unsafeRunSync()
  }