Why can't I extract with-redefs into a seperate function? - clojure

Question

I have a function that I would like to test.
(defn -main
[& args]
(let [port (Integer/parseInt (or (first args) "8080"))]
(run-jetty
app
{:port port})))
I need to mock away run-jetty for obvious reasons, so I use with-redefs to verify that the correct args are passed. This works great.
(it "should overide the port with first arg"
(with-redefs [run-jetty (fn [handler opts] [handler opts])]
(should= 8081 (jetty-port (underTest/-main "8081")))))
I'd like to extract the with-redefs call since I use it in a few more tests, so I tried this:
(defn mock-jetty
[test]
(with-redefs [run-jetty (fn [handler args] [handler args])] test))
(describe "The app"
(it "should default to port 8080"
(mock-jetty
(should= 8080 (jetty-port (underTest/-main))))))
This test calls the real run-jetty function and starts a server. Why does this happen?
EDIT
Changing extraction to a macro:
(defmacro mock-jetty
[someTest]
`(with-redefs [run-jetty (fn [handler args] [handler args])] ~someTest))
(describe "The app"
(it "should default to port 8080"
(mock-jetty
(should= 8080 (jetty-port (underTest/-main))))))
throws this exception:
Can't use qualified name as parameter: boost-bin.handler-test/handler

Answer 1

I can guess, that it is connected with the fact that with-redefs is a macro. So when you call it straight in code, it executes test body in context of redefs, while when you move it out to the function, the body (should= 8080 (jetty-port (underTest/-main))) is being executed before being passed to macro (as it always happens to functions' params)
To make it work, you could rewrite mock-jetty as a macro:
(defmacro mock-jetty
[test]
`(with-redefs [run-jetty (fn [handler# args#] [handler# args#])] ~test))
I'm pretty sure it would help