I have a test class that looks like this: ```class NetworkEitherCallAdapterTest : StringSpec({ p...

# kotest

[Lukasz Kalnik]

I have a test class that looks like this:

class NetworkEitherCallAdapterTest : StringSpec({

  private lateinit var server: MockWebServer
  private lateinit var service: CallErrorTestClient

  beforeAny {
      server = MockWebServer()
      server.start()
      service = Retrofit.Builder()
      .baseUrl(server.url("/"))
      .addConverterFactory(GsonConverterFactory.create())
      .addCallAdapterFactory(EitherCallAdapterFactory.create())
      .build()
      .create(CallErrorTestClient::class.java)
  }
  afterAny { server.shutdown() }

  "should return ResponseMock for 200 with valid JSON" {
      server.enqueue(MockResponse().setBody("""{"response":"Arrow rocks"}"""))
      val body = service.getEither()
      body shouldBe ResponseMock("Arrow rocks").right()
  }

  // More tests...

I want to run the test class 3 times with different service instances (which will use different ConverterFactory each). What is the most readable way to achieve it? I don't want to parameterize every test, I want to parameterize the whole class and repeat it.

[sam]

You could look at test factories.

[sam]

https://kotest.io/docs/framework/test-factories.html

[Lukasz Kalnik]

Thank you for the quick an helpful answer! It looks exactly like what I need ❤️

[sam]

cool 🙂

[Lukasz Kalnik]

How can I make sure though that server and service are regenerated for each test inside the factory using beforeAny?

[Lukasz Kalnik]

Basically I want to parameterize the test only on the jsonConverterFactory (which in my example actually should replace the hardcoded GsonConverterFactory.create() call). But then the server and service need to be recreated for every test inside the factory.

[Lukasz Kalnik]

I my original tests they were `lateinit var`s. I guess I just have to make them nullable in the test factory and safe-call them with ?. everytime.

[sam]

test factories have beforeTest/beforeAny and it only applies to the tests in that factory

[sam]

so you can instantiate a factory multiple times, passing in whatever parameters you want

[sam]

yeah if you want to avoid ? or !!, nothing obvious springs to mind

[sam]

we need a way to inject a fixture into a test case

[Lukasz Kalnik]

Yes, it's actually logical that I have to make these `var`s nullable, as the test factory is a function and not a class, so I cannot really cheat using lateinit as before.

[sam]

right

[Lukasz Kalnik]

It works now with !! and I don't mind it.

[sam]

you could pull the server out

[sam]

and just have start / stop inside the before/after

[Lukasz Kalnik]

True, thanks!

[Lukasz Kalnik]

No 🙂

[Lukasz Kalnik]

That's the point

[sam]

ah because you change it

[Lukasz Kalnik]

I want a new instance of the server in every test so that the server configuration doesn't leak between tests

[sam]

I guess the server is immutable so you need the var

[Lukasz Kalnik]

I want a new server in every test

[sam]

yep

[Lukasz Kalnik]

Because e.g. of such tests:

"should return IOError when no response" {
    server!!.enqueue(MockResponse().apply { socketPolicy = SocketPolicy.NO_RESPONSE })

    val body = service!!.getEither()

    body.shouldBeInstanceOf<Left<IOError>>()
      .value.cause.shouldBeInstanceOf<SocketTimeoutException>()
  }

[Lukasz Kalnik]

Maybe there is a method to reset the server config every time, but it gives me more peace of mind just to have a new server for every test.

[sam]

I guess the alternative would be to have a function that returns a server and call it inside your tests manually.

"mytest" {
  withServer { server- -> 
  }
}

[sam]

then do the setup/teardown yourself and don't use before/any

[Lukasz Kalnik]

Yes, but that's a bit counterproductive. I rather use the provided test setup/teardown facilities than copy-paste it myself.
I can live with a bit of ugliness caused by the !! operator.

[Lukasz Kalnik]

Thank you for all your help, it's amazing how easy it is to do such complex test setup in Kotest.

[sam]

yeah the power of "tests as functions" really