Async compojure

(ns my.app
  (:require
   [aleph.http               :refer :all]
   [compojure.core           :refer [defroutes GET]]
   [compojure.handler        :as handler]
   [lamina.core              :refer :all]
   [com.netflix.hystrix.core :as hystrix]
   [clj-http.client          :as client]))

(defn get-pants []
  (client/get "http://pants-service"))

(hystrix/defcommand find-pants
  {:hystrix/fallback-fn (constantly {})}
  []
  (let [response (get-pants)]
    (if (= 200 (:status response))
      (:body response)
      {})))

(defn- find-pants-observable [] (hystrix/observe #'find-pants))

(defn- pants-request-handler [channel request]
  (-> (find-pants-observable)
      (.subscribe
        #(enqueue channel {:status 200 :body %})
        #(println "ERROR " %))))

(defroutes routes
  (GET "/pants" [] (wrap-aleph-handler pants-request-handler)))

(defn make-app []
  (handler/api routes))

Async compojure test

(ns my.integration.t-app
  (:require
   [midje.sweet     :refer :all]
   [aleph.http      :refer :all]
   [lamina.core     :refer :all]
   [clj-http.client :as client]
   
   [my.app :refer :all]))

(defn do-get ([uri] (do-get uri {}))
             ([uri params]
               (let [app (wrap-ring-handler (make-app))]
                 (app ch {:uri uri :params params :request-method :get})
                 (:body @(read-channel ch)))))

(fact "pants are not trousers"
  (do-get "/pants") => "are not trousers"
  (provided
   (client/get anything) => "are not trousers"))