Creating custom HttpChecks

[Ingo Jaeckel]

Hi,

I am trying to create a custom HttpCheck that I would like to pass into Gatling's check() method:

class HttpRequestBuilder(commonAttributes: CommonAttributes, val httpAttributes: HttpAttributes) extends RequestBuilder[HttpRequestBuilder](commonAttributes) {
   ...
   def check(checks: HttpCheck*): HttpRequestBuilder = newInstance(httpAttributes.copy(checks = httpAttributes.checks ::: checks.toList))
   ...
}

Even after looking at the examples (status.is(), bodyBytes.saveAs()) I can't figure out how you would define your own subclass to perform a custom check. 

My goal is to have something similar to this:

class MyHttpCheck(wrapped: Check[Response], scope: HttpCheckScope, responseBodyUsageStrategy: Option[ResponseBodyUsageStrategy]) extends HttpCheck {
   override def check(response: Response, session: Session): Validation[CheckResult] = {
    // custom check code
    return new Success(response) // or new Failure(response)
  }
}

which would enable me to do

.http(requestTitle).post("/url").body(body).check(status.is(200), , new HttpCheck())

That said, even if I had an implementation of MyHttpCheck, I am unsure how instances of that I am unsure on how I would pass in the response into "new HttpCheck()".

Thanks,

Ingo

[Ingo Jaeckel]

I did not figure out how to create custom HttpCheck yet. But I found a workaround that works fairly well for me instead.

.exec(http(requestTitle).post(url).body(body).check(status.is(200), bodyBytes.saveAs("response"))
.exec(session => {
  val response = session("response")
  // Assert on the response stored on the response; Throw an exception to abort the session if necessary.
 
  // Return the (potentially updated) session object
  session
})
.exec(http(requestTitle).post(url).body(body).check(status.is(200), bodyBytes.saveAs("response"))

That's great because it allows me to look at the response and log out information (e.g. error codes/messages I got back from the server). I am not 100% sure if throwing an exception from the exec(session => {}) block aborts the user's session (which is what I want). Based on the output of my script it looks like the exception would just be logged. It seems like I need to add an exitHereIfFailed after the exec() to abort the session.

Thanks,

Ingo

[Stéphane LANDELLE]

This solution is easier for non Scala devs, but could be more CPU and memory expensive (build the full String in memory + store it in the Session, hence longer lifespan/GC + maybe have to remove it after usage).

Stéphane Landelle

Lead developer

slan...@gatling.io

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[Ingo Jaeckel]

Hey Stephane,

Yeah, that's what I thought. It works but the increased CPU/memory usage reduces the number of sessions I can simulate on a single gatling instance.

What can I do instead to reduce the CPU/memory impact? Do you mind outlining creating a custom HttpCheck?

Thanks,

Ingo