Ktor 1.5.4 Help


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.

Add dependencies

To use MockEngine, you need to include the ktor-client-mock artifact in the build script:

implementation "io.ktor:ktor-client-mock:$ktor_version"
<dependency> <groupId>io.ktor</groupId> <artifactId>ktor-client-mock</artifactId> <version>${ktor_version}</version> </dependency>


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"
Last modified: 19 April 2021