Hello Team, Newbie to Kotlin and Ktor. I need help in adding unit tests which uses a testing database. Is there a reference that I can follow. I'm using Ktor

2.0.2

. Basically I need to understand the setup(connection to test db and create data for testing) and teardown(cleanup of test data after all tests) parts using the

testApplication

Thanks in advance!

You can use the

TestApplicationEngine

class and setup/tear down functionality of a test framework to solve your problem. Here is an example with MongoDB:

import com.mongodb.client.MongoClient
import com.mongodb.client.MongoDatabase
import io.ktor.client.*
import io.ktor.client.request.*
import io.ktor.client.statement.*
import io.ktor.server.application.*
import io.ktor.server.response.*
import io.ktor.server.routing.*
import io.ktor.server.testing.*
import io.ktor.test.dispatcher.*
import org.junit.After
import org.junit.AfterClass
import org.junit.BeforeClass
import org.litote.kmongo.KMongo
import org.litote.kmongo.getCollection
import kotlin.test.Test
import kotlin.test.assertEquals

class DBTest {
    companion object {
        private lateinit var server: TestApplicationEngine
        private lateinit var mongoClient: MongoClient
        private lateinit var db: MongoDatabase
        private val httpClient: HttpClient get() = server.client

        @BeforeClass
        @JvmStatic
        fun setup() {
            mongoClient = KMongo.createClient()
            db = mongoClient.getDatabase("test")

            server = TestApplicationEngine(createTestEnvironment {
                developmentMode = false // to prevent a bug with a class loader in Ktor 2.0.2
                module {
                    routes(db)
                }
            })

            server.start(wait = false)
        }

        @AfterClass
        @JvmStatic
        fun tearDown() {
            server.stop()
            mongoClient.close()
        }
    }

    @After
    fun dropCollection() {
        db.getCollection<Name>().drop()
    }

    @Test
    fun checkSomeNames() = testSuspend {
        db.getCollection<Name>().insertMany(
            listOf(
                Name("John"),
                Name("Mike"),
                Name("Eddie"),
            )
        )

        assertEquals("John,Mike,Eddie", httpClient.get("/").bodyAsText())
    }

    @Test
    fun checkNoNames() = testSuspend {
        assertEquals("", httpClient.get("/").bodyAsText())
    }
}

fun Application.routes(db: MongoDatabase) {
    routing {
        get("/") {
            val collection = db.getCollection<Name>()
            val names = collection.find().toList()

            call.respondText {
                names.joinToString(separator = ",") { it.value }
            }
        }
    }
}

data class Name(val value: String)

Thanks @Aleksei Tirman [JB]. I'll cheeck this out