Added wrap-head middleware (fixes #60)

@@ -0,0 +1,14 @@
+(ns ring.middleware.head
+  "Middleware to simplify replying to HEAD requests.")
+
+(defn wrap-head
+  "Middleware that turns any HEAD request into a GET, and then sets the response
+  body to nil."
+  [handler]
+  (fn [request]
+    (if (= :head (:request-method request))
+      (-> request
+          (assoc :request-method :get)
+          (handler)
+          (assoc :body nil))
+      (handler request))))

@@ -0,0 +1,16 @@
+(ns ring.middleware.test.head
+  (:use clojure.test
+        ring.middleware.head))
+
+(defn- handler [req]
+  {:status 200
+   :headers {"X-method" (name (:request-method req))}
+   :body "Foobar"})
+
+(deftest test-wrap-head
+  (let [resp ((wrap-head handler) {:request-method :head})]
+    (is (nil? (:body resp)))
+    (is (= "get" (get-in resp [:headers "X-method"]))))
+  (let [resp ((wrap-head handler) {:request-method :post})]
+    (is (= (:body resp) "Foobar"))
+    (is (= "post" (get-in resp [:headers "X-method"])))))