How do one use the HttpClient MockEngine when JsonFeature is expected on the engine? Is there any wa...

# ktor

[jvassbo]

How do one use the HttpClient MockEngine when JsonFeature is expected on the engine? Is there any way without having to do the (de)serializing manually? See example failing test. (On Ktor 0.9.4)

-.kt

[e5l]

It looks like you try to set contentType header by hand. It's forbidden.

[e5l]

It looks like you could set Accept header to ContentType.Application.Json in fetchData and drop contentType() setup

[jvassbo]

But the contentType(ContentType.Application.Json) is needed for the JsonFeature to kick in. Removing it (or replacing with Accept header) will cause a ClassCastException since body is not a OutgoingContent

[e5l]

btw: Where did you install JsonFeature?

[e5l]

Yep. We should create OutgoingContent with proper content type here.

[jvassbo]

Production code has (excerpt):

HttpClient(Apache) {
  install(JsonFeature) {
    serializer = JacksonSerializer()
  }
}

[e5l]

Could you try to set this workaround as body?

object Json : OutgoingContent.NoContent() {
    override val contentType: ContentType get() = ContentType.Application.Json
}

Would be nice if you file an github issue. It's an API problem and I'll try to fix it asap.

[jvassbo]

Sure, I'll file a github issue. 🙂

[jvassbo]

https://github.com/ktorio/ktor/issues/615

[e5l]

Awesome. Could you test the workaround?

[jvassbo]

That leads to another problem which I didn't think of; the MockEngine of course does not know how to transform MockHttpResponse into MyResponse data class 🤔

[e5l]

You could try to make the converting interceptor 🙂