Trying to write tests on Ktor2 with kotlinx-serialization. I’m getting this error:

No request transformation found

. Does it sound familiar to someone? Looking a ktor source code, it comes from HttpRequest.kt

body as? OutgoingContent ?: error("No request transformation found: $body")

It seems related to the setBody function in my test

@Test
    fun testPostRandom() = testApplication {
        val response = <http://client.post|client.post>("/random") {
            contentType(ContentType.Application.Json)
            setBody(PostRandomRequest(listOf("Jet", "Brains")))

        }
        assertEquals("Hello World!", response.bodyAsText())
        assertEquals(HttpStatusCode.Created, response.status)
    }

You need to install the

ContentNegotiation

plugin into the client to serialize the request body:

val client = createClient {
    install(ContentNegotiation) {
        json()
    }
}
val response = <http://client.post|client.post>("/random") {
    contentType(ContentType.Application.Json)
    setBody(PostRandomRequest(listOf("Jet", "Brains")))

}
assertEquals("Hello World!", response.bodyAsText())
assertEquals(HttpStatusCode.Created, response.status)

I’ve tried this approach unsuccessfully 😞

val client = createClient {
    this@testApplication.install(ContentNegotiation)
    ...

But since I’m using HOCON config file, according to the doc:

Add modules automatically

If you have the

application.conf

file in the

resources

folder,

testApplication

loads all modules and properties specified in the configuration file automatically.

you need to bring in the right

ContentNegotiation

for the client, not the server version

It works, awesome. Thanks @phldavies 👏