test for clean_urls since headers aren't explicitly called

spec/fixtures/custom_headers/static.json

@@ -2,6 +2,10 @@
   "headers": {
     "/": {
       "Cache-Control": "no-cache"
+    },
+    "/foo.html": {
+      "X-Foo": "true"
     }
-  }
+  },
+  "clean_urls": true
 }

spec/simple_spec.rb

@@ -176,6 +176,7 @@ STATIC_JSON
 
         response = app.get("/foo.html")
         expect(response["cache-control"]).to eq(nil)
+        expect(response["X-Foo"]).to eq("true")
         expect(response.code).to eq("200")
         expect(response.body.chomp).to eq("foo")
       end