How to test zio-lambda

SimpleHandlerSpec.scala

package zio.lambda.example

import zio.Console._
import zio.Random
import zio._
import zio.json._
import zio.lambda._
import zio.test._

final case class CustomEvent(message: String)

object CustomEvent {
  implicit val decoder: JsonDecoder[CustomEvent] = DeriveJsonDecoder.gen[CustomEvent]
}

object SimpleHandler extends ZLambda[CustomEvent, String] {

  override def apply(event: CustomEvent, context: Context): RIO[ZEnv, String] =
    for {
      _ <- printLine(event.message)
    } yield "Handler ran successfully"

}

object ContextGen {
  val gen: Gen[Random with Sized, Context] =
    for {
      awsRequestId          <- Gen.string
      logGroupName          <- Gen.string
      logStreamName         <- Gen.string
      functionName          <- Gen.string
      functionVersion       <- Gen.string
      invokedFunctionArn    <- Gen.string
      remainingTimeInMillis <- Gen.long
      memoryLimitInMB       <- Gen.int
    } yield Context(
      awsRequestId,
      logGroupName,
      logStreamName,
      functionName,
      functionVersion,
      invokedFunctionArn,
      remainingTimeInMillis,
      memoryLimitInMB,
      None,
      None
    )
}

object SimpleHandlerSpec extends DefaultRunnableSpec {
  override def spec: ZSpec[Environment, Failure] =
    suite("Simple Handler spec") {
      test("should run successfully") {
        check(Gen.string, ContextGen.gen) { (message, context) =>
          SimpleHandler
            .apply(CustomEvent(message), context)
            .map(_ => assertCompletes)
        }
      }
    }
}