izumi.distage.testkit.scalatest

 trait PetStore[F[_, _]] {
   def purchasePet(name: String, cost: Int): F[Throwable, Boolean]
 }

 trait Pets[F[_, _]]
   def myPets: F[Throwable, List[String]]
 }

 type PetStoreEnv = Has[PetStore[IO]]
 type PetsEnv = Has[Pets[IO]]

 val store = new PetStore[ZIO[PetStoreEnv, _, _]] {
   def purchasePet(name: String, cost: Int): RIO[PetStoreEnv, Boolean] = ZIO.accessM(_.get.purchasePet(name, cost))
 }
 val pets = new Pets[ZIO[PetsEnv, _, _]] {
   def myPets: RIO[PetsEnv, List[String]] = ZIO.accessM(_.get.myPets)
 }

 "test purchase pets" in {
   for {
     _    <- store.purchasePet("Zab", 213)
     pets <- pets.myPets
     _    <- assertIO(pets.contains("Zab"))
   } yield ()
   // : ZIO[PetStoreEnv with PetsEnv, Throwable, Unit]
 }

 "test purchase pets" in {
   (store: PetStore[IO]) =>
     for {
       _    <- store.purchasePet("Zab", 213)
       pets <- pets.myPets
       _    <- assertIO(pets.contains("Zab"))
     } yield ()
     // : ZIO[PetsEnv, Throwable, Unit]
 }