Clojure macro to create fake java objects

fake-object.clj

;Useful macro for creating objects that can be called like java objects.
;Handy for testing clojure functions that use java objects directly.  
;Allows you easily create mock objects that can be passed into clojure functions

;EX: you have a clojure function that takes a curator LeaderLatch - the only functions you actually call are start(), hasLeadership(), and close()
;It would be a major hassle to implement a leader-latch subclass just to test that the function doesn't do any work unless it hasLeadership.

;You could implement a quick fake leader latch like:
;(fake-object
;   (close [this] (comment "no-op"))
;   (start [this] (comment "no-op"))
;   (hasLeadership [this] true))
;
; Then you can call dot-functions on your object
;(def mock
; (fake-object
;   (close [this] (comment "no-op"))
;   (start [this] (comment "no-op"))
;   (hasLeadership [this] true))
; 
; (.start mock)
; (.hasLeadership mock) ;=> returns true


(defmacro fake-object
  [& funcs]
  (let [iface (gensym "fake-object")
        func-sigs (->> funcs
                    (map #(take 2 (update-in
                                    (vec %)
                                    [1]
                                    (fn [a] (vec (rest a)))))))]
    (eval `(definterface ~iface ~@func-sigs))
    `(reify ~iface
       ~@funcs)))