Testing components with async api calls by mocking the request

I'm still in a learning phase for Cljs and Om. I'm looking into writing comopnent test. Some components have cljs-http calls to an API I created. When testing, I do not want those API calls to actually send the request, so I'm looking into mocking the request and returning a fixture. Here's an example component I have:

(defn async-component [data owner]
  (reify
    IWillMount
    (will-mount [_]
      (let [resp (go ((<! (cljs-http "/") :body))]
        (om/update! data [:objects] resp)))
    IRender
    (render [_]
      [:ul (apply map item-component data)])))

Please don't mind if the code is actually syntactically correct, I'm just showing the gist of it.

What I now want to do is test this component and the API call to see if it will render the fixture that I mock the request with. How is this done? I know cljs.test has the async block to test async code with, but all example show it testing actual code blocks that only have a go in it, not in a larger context.