Improve error messages when non-function provided as middleware

closes #3426

History.md

@@ -2,6 +2,7 @@ unreleased
 ==========
 
   * Improve error message when autoloading invalid view engine
+  * Improve error messages when non-function provided as middleware
   * Skip `Buffer` encoding when not generating ETag for small response
   * Use `safe-buffer` for improved Buffer API
   * deps: accepts@~1.3.4

lib/application.js

@@ -207,7 +207,7 @@ app.use = function use(fn) {
   var fns = flatten(slice.call(arguments, offset));
 
   if (fns.length === 0) {
-    throw new TypeError('app.use() requires middleware functions');
+    throw new TypeError('app.use() requires a middleware function')
   }
 
   // setup router

lib/router/index.js

@@ -448,14 +448,14 @@ proto.use = function use(fn) {
   var callbacks = flatten(slice.call(arguments, offset));
 
   if (callbacks.length === 0) {
-    throw new TypeError('Router.use() requires middleware functions');
+    throw new TypeError('Router.use() requires a middleware function')
   }
 
   for (var i = 0; i < callbacks.length; i++) {
     var fn = callbacks[i];
 
     if (typeof fn !== 'function') {
-      throw new TypeError('Router.use() requires middleware function but got a ' + gettype(fn));
+      throw new TypeError('Router.use() requires a middleware function but got a ' + gettype(fn))
     }
 
     // add the middleware

lib/router/route.js

@@ -175,7 +175,7 @@ Route.prototype.all = function all() {
 
     if (typeof handle !== 'function') {
       var type = toString.call(handle);
-      var msg = 'Route.all() requires callback functions but got a ' + type;
+      var msg = 'Route.all() requires a callback function but got a ' + type
       throw new TypeError(msg);
     }
 
@@ -198,7 +198,7 @@ methods.forEach(function(method){
 
       if (typeof handle !== 'function') {
         var type = toString.call(handle);
-        var msg = 'Route.' + method + '() requires callback functions but got a ' + type;
+        var msg = 'Route.' + method + '() requires a callback function but got a ' + type
         throw new Error(msg);
       }
 

test/Router.js

@@ -368,17 +368,29 @@ describe('Router', function(){
   })
 
   describe('.use', function() {
-    it('should require arguments', function(){
-      var router = new Router();
-      router.use.bind(router).should.throw(/requires middleware function/)
+    it('should require middleware', function () {
+      var router = new Router()
+      assert.throws(function () { router.use('/') }, /requires a middleware function/)
     })
 
-    it('should not accept non-functions', function(){
-      var router = new Router();
-      router.use.bind(router, '/', 'hello').should.throw(/requires middleware function.*string/)
-      router.use.bind(router, '/', 5).should.throw(/requires middleware function.*number/)
-      router.use.bind(router, '/', null).should.throw(/requires middleware function.*Null/)
-      router.use.bind(router, '/', new Date()).should.throw(/requires middleware function.*Date/)
+    it('should reject string as middleware', function () {
+      var router = new Router()
+      assert.throws(function () { router.use('/', 'foo') }, /requires a middleware function but got a string/)
+    })
+
+    it('should reject number as middleware', function () {
+      var router = new Router()
+      assert.throws(function () { router.use('/', 42) }, /requires a middleware function but got a number/)
+    })
+
+    it('should reject null as middleware', function () {
+      var router = new Router()
+      assert.throws(function () { router.use('/', null) }, /requires a middleware function but got a Null/)
+    })
+
+    it('should reject Date as middleware', function () {
+      var router = new Router()
+      assert.throws(function () { router.use('/', new Date()) }, /requires a middleware function but got a Date/)
     })
 
     it('should be called for any URL', function (done) {

test/app.use.js

@@ -1,5 +1,6 @@
 
 var after = require('after');
+var assert = require('assert')
 var express = require('..');
 var request = require('supertest');
 
@@ -253,17 +254,29 @@ describe('app', function(){
   })
 
   describe('.use(path, middleware)', function(){
-    it('should reject missing functions', function () {
-      var app = express();
-      app.use.bind(app, '/').should.throw(/requires middleware function/);
+    it('should require middleware', function () {
+      var app = express()
+      assert.throws(function () { app.use('/') }, /requires a middleware function/)
     })
 
-    it('should reject non-functions as middleware', function () {
-      var app = express();
-      app.use.bind(app, '/', 'hi').should.throw(/requires middleware function.*string/);
-      app.use.bind(app, '/', 5).should.throw(/requires middleware function.*number/);
-      app.use.bind(app, '/', null).should.throw(/requires middleware function.*Null/);
-      app.use.bind(app, '/', new Date()).should.throw(/requires middleware function.*Date/);
+    it('should reject string as middleware', function () {
+      var app = express()
+      assert.throws(function () { app.use('/', 'foo') }, /requires a middleware function but got a string/)
+    })
+
+    it('should reject number as middleware', function () {
+      var app = express()
+      assert.throws(function () { app.use('/', 42) }, /requires a middleware function but got a number/)
+    })
+
+    it('should reject null as middleware', function () {
+      var app = express()
+      assert.throws(function () { app.use('/', null) }, /requires a middleware function but got a Null/)
+    })
+
+    it('should reject Date as middleware', function () {
+      var app = express()
+      assert.throws(function () { app.use('/', new Date()) }, /requires a middleware function but got a Date/)
     })
 
     it('should strip path from req.url', function (done) {