refactor the global variables as functions

src/routes/test/clients-test.js

@@ -360,9 +360,11 @@ describe('Clients', function () {
     };
 
     // make csrf always succeed for testing
-    oauth2.csrf = function (req, res, next) {
-        req.csrfToken = function () { return hat(256); };
-        next();
+    oauth2.csrf = function () {
+        return function (req, res, next) {
+            req.csrfToken = function () { return hat(256); };
+            next();
+        };
     };
 
     function setup2(done) {