Tutorial: Testing a gRPC server

This tutorial will show you how to write a unit test for a gRPC service using an in-memory gRPC server and client.

This tutorial is aimed at developers who:

are new to Mu-Scala
have some understanding of Protobuf and .proto file syntax
have read the Getting Started guide
have followed the gRPC server and client tutorial

TODO write the tutorial. Here’s the code for the test:

import cats.effect._
import com.example.hello._
import higherkindness.mu.rpc.server._
import higherkindness.mu.rpc.testing.servers.withServerChannel
import io.grpc.ManagedChannel
import org.scalatest.flatspec.AnyFlatSpec
import scala.concurrent.ExecutionContext.Implicits

class ServerSpec extends AnyFlatSpec {

  val EC: scala.concurrent.ExecutionContext = Implicits.global

  implicit val timer: Timer[IO]     = IO.timer(EC)
  implicit val cs: ContextShift[IO] = IO.contextShift(EC)

  implicit val greeter: Greeter[IO] = new HappyGreeter[IO]

  /*
   * A cats-effect Resource that builds a gRPC server and client
   * connected to each other via an in-memory channel.
   */
  val clientResource: Resource[IO, Greeter[IO]] = for {
    sc        <- withServerChannel(Greeter.bindService[IO])
    clientRes <- Greeter.clientFromChannel[IO](IO.pure(sc.channel))
  } yield clientRes

  behavior of "RPC server"

  it should "be happy" in {
    val response: HelloResponse = clientResource
      .use(client => client.SayHello(HelloRequest("somebody")))
      .unsafeRunSync()

    assert(response.happy === true)
  }

}