make the user request and response available in skipToNextHandlerFilter

README.md

@@ -266,7 +266,7 @@ Allows you to inspect the proxy response, and decide if you want to continue pro
 
 ```js
 app.use('/proxy', proxy('www.google.com', {
-  skipToNextHandlerFilter: function(proxyRes) {
+  skipToNextHandlerFilter: function(proxyRes, userReq, userRes) {
     return proxyRes.statusCode === 404;
   }
 }));

app/steps/maybeSkipToNextHandler.js

@@ -1,14 +1,17 @@
 'use strict';
 
-function defaultSkipFilter(/* res */) {
+function defaultSkipFilter(/* proxyRes, userReq, userRes */) {
   return false;
 }
 
 function maybeSkipToNextHandler(container) {
   var resolverFn = container.options.skipToNextHandlerFilter || defaultSkipFilter;
+  var proxyRes = container.proxy.res;
+  var userReq = container.user.req;
+  var userRes = container.user.res;
 
   return Promise
-    .resolve(resolverFn(container.proxy.res))
+    .resolve(resolverFn(proxyRes, userReq, userRes))
     .then(function (shouldSkipToNext) {
       if (shouldSkipToNext) {
         container.user.res.expressHttpProxy = container.proxy;

test/maybeSkipToNextHandler.js

@@ -27,16 +27,29 @@ describe('when skipToNextHandlerFilter is defined', function () {
 
   var OUTCOMES = [
     { shouldSkip: true, expectedStatus: 200 },
-    { shouldSkip: false, expectedStatus: 404 }
+    { shouldSkip: false, expectedStatus: 404 },
+    { shouldSkip: true, expectedStatus: 200, delayedSkipProxyDecision: true },
+    { shouldSkip: false, expectedStatus: 404, delayedSkipProxyDecision: false }
   ];
 
   OUTCOMES.forEach(function (outcome) {
     describe('and returns ' + outcome.shouldSkip, function () {
       it('express-http-proxy' + (outcome.shouldSkip ? ' skips ' : ' doesnt skip ') + 'to next()', function (done) {
 
+        if (outcome.delayedSkipProxyDecision !== undefined) {
+          app.use(function (req, res, next) {
+            res.locals.skipProxyDecisionPromise = new Promise(function (resolve) {
+              setTimeout(function () {
+                resolve(outcome.delayedSkipProxyDecision);
+              }, 50);
+            });
+            next();
+          });
+        }
+
         app.use('/proxy', proxy('http://127.0.0.1:12345', {
-          skipToNextHandlerFilter: function (/*res*/) {
-            return outcome.shouldSkip;
+          skipToNextHandlerFilter: function (proxyRes, userReq, userRes) {
+            return userRes.locals.skipProxyDecisionPromise || outcome.shouldSkip;
           }
         }));