Testing

note

This help topic is in development and will be updated in the future.

Ktor exposes a MockEngine for the HttpClient. This engine allows simulating HTTP calls without actually connecting to the endpoint. It allows to set a code block, that can handle the request and generates a response.

Usage

The usage is straightforward: the MockEngine class has a method addHandler in MockEngineConfig, that receives a block/callback that will handle the request. This callback receives an HttpRequest as a parameter, and must return a HttpResponseData. There are many helper methods to construct the response.

Full API description and list of helper methods could be found here.

A sample illustrating this:

val client = HttpClient(MockEngine) {
    engine {
        addHandler { request ->
            when (request.url.fullUrl) {
                "https://example.org/" -> {
                    val responseHeaders = headersOf("Content-Type" to listOf(ContentType.Text.Plain.toString()))
                    respond("Hello, world", headers = responseHeaders)
                }
                else -> error("Unhandled ${request.url.fullUrl}")
            }
        }
    }
}
private val Url.hostWithPortIfRequired: String get() = if (port == protocol.defaultPort) host else hostWithPort
private val Url.fullUrl: String get() = "${protocol.name}://$hostWithPortIfRequired$fullPath"