Provide matched route to middleware

- set `__mountpath` in `.use()`
- override `process_params` to add `req.matchedRoutes`

`req.matchedRoutes` is a proposed addition to express v5:
pillarjs/router#34

Doing this because in goodeggs-stats, we need to know what route we are
currently on when we are publishing metrics to librato. In express v4
there is no mechanism to do this, if the routes have parameters in them
(like :id, etc) or if they have nesting (given /foo/bar, the middleware
for /foo has no knowledge of /bar and vice-versa).

src/index.js

@@ -132,7 +132,8 @@ export default class Router extends BaseRouter {
       return _.isFunction(router.resolveCustomSecurity);
     }
 
-    if (_.isString(path)) {
+    const pathIsString = _.isString(path);
+    if (pathIsString) {
       let {pathDefinition} = this.getPathDefinitionMatching(path);
       if (_.isNil(pathDefinition)) {
         pathDefinition = createPathDefinition({path});
@@ -147,7 +148,39 @@ export default class Router extends BaseRouter {
         this.pathDefinitions.push(...innerRouter.pathDefinitions);
       }
     }
+
+    let offset = this.stack.length;
     BaseRouter.prototype.use.apply(this, arguments);
+
+    /* so that in our monkey patch of process_params, we can know about the
+     * path of this part of the route */
+    if (pathIsString) {
+      for (; offset < this.stack.length; offset++) {
+        const layer = this.stack[offset];
+        // I'm not sure if my check for `fast_slash` is the way to go here
+        // But if I don't check for it, each stack element will add a slash to the path
+        if (layer && layer.regexp && !layer.regexp.fast_slash) {
+          layer.__mountpath = path;
+        }
+      }
+    }
+  }
+
+  process_params (layer, called, req, res, done) {
+    var path =
+      _.get(req, 'route.path',
+        _.get(req, 'route.regexp.source',
+          _.get(layer, '__mountpath',
+            '')));
+
+    if (req.matchedRoutes == null) req.matchedRoutes = [];
+    req.__route = (req.__route || '') + path;
+
+    if (!_.isEmpty(path)) {
+      req.matchedRoutes.push(path);
+    }
+
+    return BaseRouter.prototype.process_params.apply(this, arguments);
   }
 
   bouncer (bouncer) {

test.js

@@ -38,6 +38,28 @@ describe('use()', function () {
     return withRunningServer(router)
     .then(() => expectRequest('GET', '/foo').toReturnCode(200));
   });
+
+  it('provides req.matchedRoute to middlewares even when 404', function () {
+    const router = buildRouter();
+    const subRouter = new Router();
+    subRouter.secureSubpath({
+      path: '/nested',
+      bouncers: [
+        _.constant(Router.AUTHENTICATE),
+        _.constant(Router.AUTHORIZE),
+      ],
+    });
+    router.use('/base/:baseId', subRouter);
+    router.use((req, res, next) => {
+      res.status(404);
+      res.json(req.matchedRoutes);
+    });
+    return withRunningServer(router)
+    .then(() =>
+      expectRequest('GET', '/base/2/nested/239847')
+        .toReturnBody(['/base/:baseId', '/nested'])
+    );
+  });
 });
 
 describe('secureEndpoint()', function () {
@@ -169,6 +191,29 @@ describe('secureEndpoint()', function () {
       .then(() => expectRequest('POST', '/foo').toReturnCode(200))
       .then(() => expectRequest('POST', '/foo/123').toReturnCode(403));
   });
+
+  it('provides req.matchedRoute to middlewares', function () {
+    const router = buildRouter();
+    const subRouter = new Router();
+    subRouter.secureEndpoint({
+      method: 'GET',
+      path: '/nested/:nestedId',
+      bouncers: [
+        _.constant(Router.AUTHENTICATE),
+        _.constant(Router.AUTHORIZE),
+      ],
+      middleware: (req, res) => {
+        res.json(req.matchedRoutes);
+        res.sendStatus(200);
+      },
+    });
+    router.use('/base/:baseId', subRouter);
+    return withRunningServer(router)
+    .then(() =>
+      expectRequest('GET', '/base/2/nested/239847')
+        .toReturnBody(['/base/:baseId', '/nested/:nestedId'])
+    );
+  });
 });
 
 describe('secureSubpath()', function () {
@@ -221,6 +266,28 @@ describe('secureSubpath()', function () {
     .then(() => expectRequest('GET', '/sub/subsub/foo').toReturnCode(200))
     .then(() => expectRequest('GET', '/sub/foo').toReturnCode(401));
   });
+
+  it('provides req.matchedRoute to middlewares', function () {
+    const router = buildRouter();
+    const subRouter = new Router();
+    subRouter.secureSubpath({
+      path: '/nested',
+      bouncers: [
+        _.constant(Router.AUTHENTICATE),
+        _.constant(Router.AUTHORIZE),
+      ],
+    })
+    .get('/:nestedId', (req, res) => {
+      res.json(req.matchedRoutes);
+      res.sendStatus(200);
+    });
+    router.use('/base/:baseId', subRouter);
+    return withRunningServer(router)
+    .then(() =>
+      expectRequest('GET', '/base/2/nested/239847')
+        .toReturnBody(['/base/:baseId', '/nested', '/:nestedId'])
+    );
+  });
 });
 
 describe('bouncer()', function () {