use dependency injection in order to make include resolving testable

project.clj

@@ -29,7 +29,8 @@
                  [prone "1.1.4"]
                  [ring/ring-anti-forgery "1.1.0"]
                  [ring-server "0.4.0"]
-                 [selmer "1.11.0"]]
+                 [selmer "1.11.0"]
+                 [com.stuartsierra/component "0.3.2"]]
 
   :repl-options {:init-ns smeagol.repl}
 

src/smeagol/include.clj

@@ -0,0 +1,11 @@
+(ns smeagol.include
+  (:require
+    [com.stuartsierra.component :as component]))
+
+(defrecord Resolver [resolver-fn])
+
+(defn new-resolver [resolver-fn]
+  (map->Resolver {:resolver-fn resolver-fn}))
+
+(defn resolve-include [resolver uri]
+  (apply (:resolver-fn resolver) [uri]))

test/smeagol/test/include.clj

@@ -0,0 +1,16 @@
+(ns smeagol.test.include
+  (:require [clojure.test :refer :all]
+            [com.stuartsierra.component :as component]
+            [smeagol.include :as sut]))
+
+(defn test-include-resolver [uri]
+  (cond
+    (= uri "./simple.md") "Simple content."))
+
+(def system-under-test
+  (component/system-map
+    :resolver (sut/new-resolver test-include-resolver)))
+
+(deftest test-local-links
+  (testing "Rewriting of local links"
+    (is (= "Simple content." (sut/resolve-include (:resolver system-under-test) "./simple.md")))))