Is there any way to make a fake call from Ktor to itself, to make request pass through all pipeline? - kotlin

Question

I have an ktor web server that successfully responds on http requests. Now there is a need to read data from kafka's topic and process it.
Is there any way send the data I've read to ktor, like this data came from outside, to make it pass through all pipeline, like ContentNegotiation and other features?
Application class has method execute(), which takes ApplicationCall, but I've found zero examples - how can I fill my implementation of this class properly. Especially route - do I need the real one? Would be nice if this route would be private and would be unavailable from the outside.

Answer 1

You can use the withTestApplication function to test your application's modules without making an actual network connection. Here is an example:
import io.ktor.application.*
import io.ktor.http.*
import io.ktor.request.*
import io.ktor.response.*
import io.ktor.routing.*
import io.ktor.server.testing.*
import org.junit.jupiter.api.Test
import kotlin.test.assertEquals
class SimpleTest {
#Test
fun test() = withTestApplication {
application.module()
// more modules to test here
handleRequest(HttpMethod.Post, "/post") {
setBody("kafka data")
}.response.let { response ->
assertEquals("I get kafka data", response.content)
}
}
}
fun Application.module() {
routing {
post("/post") {
call.respondText { "I get ${call.receiveText()}" }
}
}
}

Answer 2

I think that #AlekseiTirman answer is great and most probably you should go for it
But I have to mention that it's easy to do it even in "real life" run. Your local machine ip is 0.0.0.0, you can get port from the env variable, so you just can create a simple HttpClient and send a request:
CoroutineScope(Dispatchers.IO).launch {
delay(1000)
val client = HttpClient {
defaultRequest {
// actually this is already a default value so no need to setting it
host = "0.0.0.0"
port = environment.config.property("ktor.deployment.port").getString().toInt()
}
}
val result = client.get<String>("good")
println("local response $result")
}
routing {
get("good") {
call.respond("hello world")
}
}