Hi all, has anybody of you experience with testing multipart uploads using the client's

MockEngine

? I want to test my client which is building a

MultiPartFormDataContent

using the

formData

builder (which by the way seems to lack support for appending files?). Now my problem is that the request body in the

MockEngine

is just a

MultiPartFormDataContent

only exposing properties of

OutgoingContent.WriteChannelContent

, which means I can only get the full body with all boundary strings and headers written in it. My current workaround is to more or less split the full body into somehow manageable parts, sadly all methods I could find for parsing

multipart/form-data

in ktor are either

internal

already or marked as deprecated as they will become

internal

in the future. Am I overlooking something or is ktor's api just lacking in this area as of now?

You can add

@OptIn(InternalAPI::class)

annotation to get rid of the internal API warning. Here is a complete example of the test:

import io.ktor.client.*
import io.ktor.client.engine.mock.*
import io.ktor.client.request.forms.*
import io.ktor.http.*
import io.ktor.http.cio.*
import io.ktor.http.content.*
import io.ktor.util.*
import io.ktor.utils.io.*
import io.ktor.utils.io.core.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.runBlocking
import org.junit.Test
import java.io.File
import kotlin.test.assertEquals

class SomeTest {

    @OptIn(InternalAPI::class)
    @Test
    fun test(): Unit = runBlocking {
        val client = HttpClient(MockEngine) {
            engine {
                addHandler { request ->
                    val body = request.body as OutgoingContent.WriteChannelContent
                    val channel = GlobalScope.writer(<http://Dispatchers.IO|Dispatchers.IO>) { body.writeTo(channel) }.channel
                    val result = CIOMultipartDataBase(Dispatchers.Unconfined, channel, body.contentType.toString(), body.contentLength)
                    val parts = result.readAllParts()

                    val description = parts[0] as PartData.FormItem
                    assertEquals("description", description.name)
                    assertEquals("Ktor logo", description.value)

                    val file = parts[1] as PartData.FileItem
                    assertEquals("image", file.name)
                    assertEquals("wiki.txt", file.originalFileName)
                    assertEquals("", file.provider().readText())

                    respond("")
                }
            }
        }

        client.submitFormWithBinaryData<String>(
            url = "<http://localhost:8080/upload>",
            formData = formData {
                append("description", "Ktor logo")
                append("image", File("files/wiki.txt").readBytes(), Headers.build {
                    append(HttpHeaders.ContentType, "plain/text")
                    append(HttpHeaders.ContentDisposition, "filename=wiki.txt")
                })
            }
        )
    }
}

thanks