refactor Application into a class

Readme.md

@@ -44,8 +44,8 @@ $ npm install koa
 ## Example
 
 ```js
-const koa = require('koa');
+const Koa = require('koa');
-const app = koa();
+const app = new Koa();
 
 // logger
 

benchmarks/experimental/async.js

@@ -2,8 +2,8 @@
 'use strict';
 
 const http = require('http');
-const koa = require('../..');
+const Koa = require('../..');
-const app = koa();
+const app = new Koa();
 
 app.experimental = true;
 

benchmarks/middleware.js

@@ -2,8 +2,8 @@
 'use strict';
 
 const http = require('http');
-const koa = require('..');
+const Koa = require('..');
-const app = koa();
+const app = new Koa();
 
 // number of middleware
 

docs/api/index.md

@@ -30,7 +30,7 @@ $ node my-koa-app.js
 
 ```js
 var koa = require('koa');
-var app = koa();
+var app = new Koa();
 
 app.use(function *(){
   this.body = 'Hello World';
@@ -56,7 +56,7 @@ app.listen(3000);
 
 ```js
 var koa = require('koa');
-var app = koa();
+var app = new Koa();
 
 // x-response-time
 
@@ -106,7 +106,7 @@ app.listen(3000);
 
 ```js
 var koa = require('koa');
-var app = koa();
+var app = new Koa();
 app.listen(3000);
 ```
 
@@ -115,7 +115,7 @@ app.listen(3000);
 ```js
 var http = require('http');
 var koa = require('koa');
-var app = koa();
+var app = new Koa();
 http.createServer(app.callback()).listen(3000);
 ```
 
@@ -125,7 +125,7 @@ http.createServer(app.callback()).listen(3000);
 ```js
 var http = require('http');
 var koa = require('koa');
-var app = koa();
+var app = new Koa();
 http.createServer(app.callback()).listen(3000);
 http.createServer(app.callback()).listen(3001);
 ```

lib/application.js

@@ -24,159 +24,155 @@ const only = require('only');
 const co = require('co');
 
 /**
- * Application prototype.
+ * Expose `Application` class.
+ * Inherits from `Emitter.prototype`.
  */
 
-const app = Application.prototype;
+module.exports = class Application extends Emitter {
 
-/**
+  /**
- * Expose `Application`.
+   * Initialize a new `Application`.
- */
+   *
+   * @api public
+   */
 
-module.exports = Application;
+  constructor() {
+    super();
 
-/**
+    if (!(this instanceof Application)) return new Application;
- * Initialize a new `Application`.
+    this.env = process.env.NODE_ENV || 'development';
- *
+    this.subdomainOffset = 2;
- * @api public
+    this.middleware = [];
- */
+    this.context = Object.create(context);
+    this.request = Object.create(request);
+    this.response = Object.create(response);
+  }
+
+  /**
+   * Shorthand for:
+   *
+   *    http.createServer(app.callback()).listen(...)
+   *
+   * @param {Mixed} ...
+   * @return {Server}
+   * @api public
+   */
+
+  listen() {
+    debug('listen');
+    const server = http.createServer(this.callback());
+    return server.listen.apply(server, arguments);
+  }
+
+  /**
+   * Return JSON representation.
+   * We only bother showing settings.
+   *
+   * @return {Object}
+   * @api public
+   */
+
+  toJSON() {
+    return only(this, [
+      'subdomainOffset',
+      'env'
+    ]);
+  }
+
+  inspect() {
+    return this.toJSON();
+  }
+
+  /**
+   * Use the given middleware `fn`.
+   *
+   * @param {GeneratorFunction} fn
+   * @return {Application} self
+   * @api public
+   */
+
+  use(fn) {
+    if (!this.experimental) {
+      // es7 async functions are allowed
+      assert(fn && 'GeneratorFunction' == fn.constructor.name, 'app.use() requires a generator function');
+    }
+    debug('use %s', fn._name || fn.name || '-');
+    this.middleware.push(fn);
+    return this;
+  }
+
+  /**
+   * Return a request handler callback
+   * for node's native http server.
+   *
+   * @return {Function}
+   * @api public
+   */
+
+  callback() {
+    const fn = this.experimental
+      ? compose_es7(this.middleware)
+      : co.wrap(compose(this.middleware));
+
+    if (!this.listeners('error').length) this.on('error', this.onerror);
+
+    return (req, res) => {
+      res.statusCode = 404;
+      const ctx = this.createContext(req, res);
+      onFinished(res, ctx.onerror);
+      fn.call(ctx).then(function () {
+        respond.call(ctx);
+      }).catch(ctx.onerror);
+    }
+  }
+
+  /**
+   * Initialize a new context.
+   *
+   * @api private
+   */
+
+  createContext(req, res) {
+    const context = Object.create(this.context);
+    const request = context.request = Object.create(this.request);
+    const response = context.response = Object.create(this.response);
+    context.app = request.app = response.app = this;
+    context.req = request.req = response.req = req;
+    context.res = request.res = response.res = res;
+    request.ctx = response.ctx = context;
+    request.response = response;
+    response.request = request;
+    context.onerror = context.onerror.bind(context);
+    context.originalUrl = request.originalUrl = req.url;
+    context.cookies = new Cookies(req, res, this.keys);
+    context.accept = request.accept = accepts(req);
+    context.state = {};
+    return context;
+  }
+
+  /**
+   * Default error handler.
+   *
+   * @param {Error} err
+   * @api private
+   */
+
+  onerror(err) {
+    assert(err instanceof Error, `non-error thrown: ${err}`);
+
+    if (404 == err.status || err.expose) return;
+    if (this.silent) return;
+    // DEPRECATE env-specific logging in v2
+    if ('test' == this.env) return;
+
+    const msg = err.stack || err.toString();
+    console.error();
+    console.error(msg.replace(/^/gm, '  '));
+    console.error();
+  }
 
-function Application() {
-  if (!(this instanceof Application)) return new Application;
-  this.env = process.env.NODE_ENV || 'development';
-  this.subdomainOffset = 2;
-  this.middleware = [];
-  this.context = Object.create(context);
-  this.request = Object.create(request);
-  this.response = Object.create(response);
 }
 
-/**
- * Inherit from `Emitter.prototype`.
- */
-
-Object.setPrototypeOf(Application.prototype, Emitter.prototype);
-
-/**
- * Shorthand for:
- *
- *    http.createServer(app.callback()).listen(...)
- *
- * @param {Mixed} ...
- * @return {Server}
- * @api public
- */
-
-app.listen = function(){
-  debug('listen');
-  const server = http.createServer(this.callback());
-  return server.listen.apply(server, arguments);
-};
-
-/**
- * Return JSON representation.
- * We only bother showing settings.
- *
- * @return {Object}
- * @api public
- */
-
-app.inspect =
-app.toJSON = function(){
-  return only(this, [
-    'subdomainOffset',
-    'env'
-  ]);
-};
-
-/**
- * Use the given middleware `fn`.
- *
- * @param {GeneratorFunction} fn
- * @return {Application} self
- * @api public
- */
-
-app.use = function(fn){
-  if (!this.experimental) {
-    // es7 async functions are allowed
-    assert(fn && 'GeneratorFunction' == fn.constructor.name, 'app.use() requires a generator function');
-  }
-  debug('use %s', fn._name || fn.name || '-');
-  this.middleware.push(fn);
-  return this;
-};
-
-/**
- * Return a request handler callback
- * for node's native http server.
- *
- * @return {Function}
- * @api public
- */
-
-app.callback = function(){
-  const fn = this.experimental
-    ? compose_es7(this.middleware)
-    : co.wrap(compose(this.middleware));
-
-  if (!this.listeners('error').length) this.on('error', this.onerror);
-
-  return (req, res) => {
-    res.statusCode = 404;
-    const ctx = this.createContext(req, res);
-    onFinished(res, ctx.onerror);
-    fn.call(ctx).then(function () {
-      respond.call(ctx);
-    }).catch(ctx.onerror);
-  }
-};
-
-/**
- * Initialize a new context.
- *
- * @api private
- */
-
-app.createContext = function(req, res){
-  const context = Object.create(this.context);
-  const request = context.request = Object.create(this.request);
-  const response = context.response = Object.create(this.response);
-  context.app = request.app = response.app = this;
-  context.req = request.req = response.req = req;
-  context.res = request.res = response.res = res;
-  request.ctx = response.ctx = context;
-  request.response = response;
-  response.request = request;
-  context.onerror = context.onerror.bind(context);
-  context.originalUrl = request.originalUrl = req.url;
-  context.cookies = new Cookies(req, res, this.keys);
-  context.accept = request.accept = accepts(req);
-  context.state = {};
-  return context;
-};
-
-/**
- * Default error handler.
- *
- * @param {Error} err
- * @api private
- */
-
-app.onerror = function(err){
-  assert(err instanceof Error, `non-error thrown: ${err}`);
-
-  if (404 == err.status || err.expose) return;
-  if (this.silent) return;
-  // DEPRECATE env-specific logging in v2
-  if ('test' == this.env) return;
-
-  const msg = err.stack || err.toString();
-  console.error();
-  console.error(msg.replace(/^/gm, '  '));
-  console.error();
-};
-
 /**
  * Response helper.
  */

test/application/context.js

@@ -3,12 +3,12 @@
 
 const request = require('supertest');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.context', function(){
-  const app1 = koa();
+  const app1 = new Koa();
   app1.context.msg = 'hello';
-  const app2 = koa();
+  const app2 = new Koa();
 
   it('should merge properties', function(done){
     app1.use(function *(next){

test/application/index.js

@@ -3,11 +3,11 @@
 
 const request = require('supertest');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app', function(){
   it('should handle socket errors', function(done){
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *(next){
       // triggers this.socket.writable == false
@@ -25,7 +25,7 @@ describe('app', function(){
   })
 
   it('should not .writeHead when !socket.writable', function(done){
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *(next){
       // set .writable to false
@@ -49,7 +49,7 @@ describe('app', function(){
   it('should set development env when NODE_ENV missing', function(){
     const NODE_ENV = process.env.NODE_ENV;
     process.env.NODE_ENV = '';
-    const app = koa();
+    const app = new Koa();
     process.env.NODE_ENV = NODE_ENV;
     assert.equal(app.env, 'development');
   })

test/application/inspect.js

@@ -1,11 +1,11 @@
 
 'use strict';
 
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.inspect()', function(){
   it('should work', function(){
-    const app = koa();
+    const app = new Koa();
     const util = require('util');
     const str = util.inspect(app);
   })

test/application/onerror.js

@@ -2,12 +2,12 @@
 'use strict';
 
 const stderr = require('test-console').stderr;
-const koa = require('../..');
+const Koa = require('../..');
 const AssertionError = require('assert').AssertionError;
 
 describe('app.onerror(err)', function(){
   it('should throw an error if a non-error is given', function(done){
-    const app = koa();
+    const app = new Koa();
 
     try {
       app.onerror('foo');
@@ -22,7 +22,7 @@ describe('app.onerror(err)', function(){
   })
 
   it('should do nothing if status is 404', function(done){
-    const app = koa();
+    const app = new Koa();
     const err = new Error();
 
     err.status = 404;
@@ -37,7 +37,7 @@ describe('app.onerror(err)', function(){
   })
 
   it('should do nothing if .silent', function(done){
-    const app = koa();
+    const app = new Koa();
     app.silent = true;
     const err = new Error();
 
@@ -51,7 +51,7 @@ describe('app.onerror(err)', function(){
   })
 
   it('should log the error to stderr', function(done){
-    const app = koa();
+    const app = new Koa();
     app.env = 'dev';
 
     const err = new Error();
@@ -67,7 +67,7 @@ describe('app.onerror(err)', function(){
   })
 
   it('should use err.toString() instad of err.stack', function(done){
-    const app = koa();
+    const app = new Koa();
     app.env = 'dev';
 
     const err = new Error('mock stack null');

test/application/request.js

@@ -3,12 +3,12 @@
 
 const request = require('supertest');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.request', function(){
-  const app1 = koa();
+  const app1 = new Koa();
   app1.request.message = 'hello';
-  const app2 = koa();
+  const app2 = new Koa();
 
   it('should merge properties', function(done){
     app1.use(function *(next){

test/application/respond.js

@@ -4,13 +4,13 @@
 const request = require('supertest');
 const statuses = require('statuses');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 const fs = require('fs');
 
 describe('app.respond', function(){
   describe('when this.respond === false', function(){
     it('should bypass app.respond', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = 'Hello';
@@ -36,7 +36,7 @@ describe('app.respond', function(){
 
   describe('when HEAD is used', function(){
     it('should not respond with the body', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = 'Hello';
@@ -57,7 +57,7 @@ describe('app.respond', function(){
     })
 
     it('should keep json headers', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = { hello: 'world' };
@@ -78,7 +78,7 @@ describe('app.respond', function(){
     })
 
     it('should keep string headers', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = 'hello world';
@@ -99,7 +99,7 @@ describe('app.respond', function(){
     })
 
     it('should keep buffer headers', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = new Buffer('hello world');
@@ -120,7 +120,7 @@ describe('app.respond', function(){
     })
 
     it('should respond with a 404 if no body was set', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
 
@@ -134,7 +134,7 @@ describe('app.respond', function(){
     })
 
     it('should respond with a 200 if body = ""', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = '';
@@ -148,7 +148,7 @@ describe('app.respond', function(){
     })
 
     it('should not overwrite the content-type', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 200;
@@ -166,7 +166,7 @@ describe('app.respond', function(){
 
   describe('when no middleware are present', function(){
     it('should 404', function(done){
-      const app = koa();
+      const app = new Koa();
 
       const server = app.listen();
 
@@ -178,7 +178,7 @@ describe('app.respond', function(){
 
   describe('when res has already been written to', function(){
     it('should not cause an app error', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(next){
         const res = this.res;
@@ -209,7 +209,7 @@ describe('app.respond', function(){
     })
 
     it('should send the right body', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(next){
         const res = this.res;
@@ -233,7 +233,7 @@ describe('app.respond', function(){
   describe('when .body is missing', function(){
     describe('with status=400', function(){
       it('should respond with the associated status message', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.status = 400;
@@ -251,7 +251,7 @@ describe('app.respond', function(){
 
     describe('with status=204', function(){
       it('should respond without a body', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.status = 204;
@@ -274,7 +274,7 @@ describe('app.respond', function(){
 
     describe('with status=205', function(){
       it('should respond without a body', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.status = 205;
@@ -297,7 +297,7 @@ describe('app.respond', function(){
 
     describe('with status=304', function(){
       it('should respond without a body', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.status = 304;
@@ -320,7 +320,7 @@ describe('app.respond', function(){
 
     describe('with custom status=700', function(){
       it('should respond with the associated status message', function (done){
-        const app = koa();
+        const app = new Koa();
         statuses['700'] = 'custom status';
 
         app.use(function *(){
@@ -343,7 +343,7 @@ describe('app.respond', function(){
 
     describe('with custom statusMessage=ok', function(){
       it('should respond with the custom status message', function (done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.status = 200;
@@ -366,7 +366,7 @@ describe('app.respond', function(){
 
     describe('with custom status without message', function (){
       it('should respond with the status code number', function (done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           this.res.statusCode = 701;
@@ -384,7 +384,7 @@ describe('app.respond', function(){
 
   describe('when .body is a null', function(){
     it('should respond 204 by default', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = null;
@@ -405,7 +405,7 @@ describe('app.respond', function(){
     })
 
     it('should respond 204 with status=200', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 200;
@@ -427,7 +427,7 @@ describe('app.respond', function(){
     })
 
     it('should respond 205 with status=205', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 205;
@@ -449,7 +449,7 @@ describe('app.respond', function(){
     })
 
     it('should respond 304 with status=304', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 304;
@@ -473,7 +473,7 @@ describe('app.respond', function(){
 
   describe('when .body is a string', function(){
     it('should respond', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = 'Hello';
@@ -489,7 +489,7 @@ describe('app.respond', function(){
 
   describe('when .body is a Buffer', function(){
     it('should respond', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = new Buffer('Hello');
@@ -505,7 +505,7 @@ describe('app.respond', function(){
 
   describe('when .body is a Stream', function(){
     it('should respond', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = fs.createReadStream('package.json');
@@ -527,7 +527,7 @@ describe('app.respond', function(){
     })
 
     it('should strip content-length when overwriting', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = 'hello';
@@ -550,7 +550,7 @@ describe('app.respond', function(){
     })
 
     it('should keep content-length if not overwritten', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.length = fs.readFileSync('package.json').length;
@@ -573,7 +573,7 @@ describe('app.respond', function(){
     })
 
     it('should keep content-length if overwritten with the same stream', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.length = fs.readFileSync('package.json').length;
@@ -598,7 +598,7 @@ describe('app.respond', function(){
     })
 
     it('should handle errors', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.set('Content-Type', 'application/json; charset=utf-8');
@@ -615,7 +615,7 @@ describe('app.respond', function(){
     })
 
     it('should handle errors when no content status', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 204;
@@ -631,7 +631,7 @@ describe('app.respond', function(){
 
 
     it('should handle all intermediate stream body errors', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = fs.createReadStream('does not exist');
@@ -649,7 +649,7 @@ describe('app.respond', function(){
 
   describe('when .body is an Object', function(){
     it('should respond with json', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = { hello: 'world' };
@@ -666,7 +666,7 @@ describe('app.respond', function(){
 
   describe('when an error occurs', function(){
     it('should emit "error" on the app', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         throw new Error('boom');
@@ -684,7 +684,7 @@ describe('app.respond', function(){
 
     describe('with an .expose property', function(){
       it('should expose the message', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           const err = new Error('sorry!');
@@ -702,7 +702,7 @@ describe('app.respond', function(){
 
     describe('with a .status property', function(){
       it('should respond with .status', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(){
           const err = new Error('s3 explodes');
@@ -718,7 +718,7 @@ describe('app.respond', function(){
     })
 
     it('should respond with 500', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         throw new Error('boom!');
@@ -733,7 +733,7 @@ describe('app.respond', function(){
     })
 
     it('should be catchable', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(next){
         try {
@@ -760,7 +760,7 @@ describe('app.respond', function(){
 
   describe('when status and body property', function(){
     it('should 200', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 304;
@@ -777,7 +777,7 @@ describe('app.respond', function(){
     })
 
     it('should 204', function(done) {
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = 200;

test/application/response.js

@@ -3,12 +3,12 @@
 
 const request = require('supertest');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.response', function(){
-  const app1 = koa();
+  const app1 = new Koa();
   app1.response.msg = 'hello';
-  const app2 = koa();
+  const app2 = new Koa();
 
   it('should merge properties', function(done){
     app1.use(function *(next){

test/application/toJSON.js

@@ -1,11 +1,11 @@
 
 'use strict';
 
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.toJSON()', function(){
   it('should work', function(){
-    const app = koa();
+    const app = new Koa();
     const obj = app.toJSON();
 
     obj.should.eql({

test/application/use.js

@@ -2,11 +2,11 @@
 'use strict';
 
 const request = require('supertest');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('app.use(fn)', function(){
   it('should compose middleware', function(done){
-    const app = koa();
+    const app = new Koa();
     const calls = [];
 
     app.use(function *(next){
@@ -40,7 +40,7 @@ describe('app.use(fn)', function(){
   })
 
   it('should error when a non-generator function is passed', function(){
-    const app = koa();
+    const app = new Koa();
 
     try {
       app.use(function(){});
@@ -50,7 +50,7 @@ describe('app.use(fn)', function(){
   })
 
   it('should not error when a non-generator function is passed when .experimental=true', function(){
-    const app = koa();
+    const app = new Koa();
     app.experimental = true;
     app.use(function(){});
   })

test/context/cookies.js

@@ -2,11 +2,11 @@
 'use strict';
 
 const request = require('supertest');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('ctx.cookies.set()', function(){
   it('should set an unsigned cookie', function(done){
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *(next){
       this.cookies.set('name', 'jon');
@@ -32,7 +32,7 @@ describe('ctx.cookies.set()', function(){
   describe('with .signed', function(){
     describe('when no .keys are set', function(){
       it('should error', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(next){
           try {
@@ -49,7 +49,7 @@ describe('ctx.cookies.set()', function(){
     })
 
     it('should send a signed cookie', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.keys = ['a', 'b'];
 

test/context/onerror.js

@@ -2,11 +2,11 @@
 'use strict';
 
 const request = require('supertest');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('ctx.onerror(err)', function(){
   it('should respond', function(done){
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *(next){
       this.body = 'something else';
@@ -25,7 +25,7 @@ describe('ctx.onerror(err)', function(){
   })
 
   it('should unset all headers', function(done){
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *(next){
       this.set('Vary', 'Accept-Encoding');
@@ -55,7 +55,7 @@ describe('ctx.onerror(err)', function(){
   describe('when invalid err.status', function(){
     describe('not number', function(){
       it('should respond 500', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(next){
           this.body = 'something else';
@@ -76,7 +76,7 @@ describe('ctx.onerror(err)', function(){
 
     describe('not http status code', function(){
       it('should respond 500', function(done){
-        const app = koa();
+        const app = new Koa();
 
         app.use(function *(next){
           this.body = 'something else';
@@ -98,7 +98,7 @@ describe('ctx.onerror(err)', function(){
 
   describe('when non-error thrown', function(){
     it('should response non-error thrown message', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(next){
         throw 'string error';

test/context/state.js

@@ -3,11 +3,11 @@
 
 const request = require('supertest');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('ctx.state', function() {
   it('should provide a ctx.state namespace', function(done) {
-    const app = koa();
+    const app = new Koa();
 
     app.use(function *() {
       assert.deepEqual(this.state, {});

test/experimental/async.js

@@ -6,11 +6,11 @@
  */
 
 const request = require('supertest');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('.experimental=true', function () {
   it('should support async functions', function (done) {
-    const app = koa();
+    const app = new Koa();
     app.experimental = true;
     app.use(async function (next) {
       const string = await Promise.resolve('asdf');

test/helpers/context.js

@@ -2,7 +2,7 @@
 'use strict';
 
 const Stream = require('stream');
-const koa = require('../..');
+const Koa = require('../..');
 
 exports = module.exports = function(req, res){
   const socket = new Stream.Duplex();
@@ -11,7 +11,7 @@ exports = module.exports = function(req, res){
   res.getHeader = function(k){ return res._headers[k.toLowerCase()] };
   res.setHeader = function(k, v){ res._headers[k.toLowerCase()] = v };
   res.removeHeader = function(k, v){ delete res._headers[k.toLowerCase()] };
-  return koa().createContext(req, res);
+  return (new Koa()).createContext(req, res);
 }
 
 exports.request = function(req, res){

test/request/href.js

@@ -3,7 +3,7 @@
 
 const Stream = require('stream');
 const http = require('http');
-const koa = require('../../');
+const Koa = require('../../');
 const context = require('../helpers/context');
 
 describe('ctx.href', function(){
@@ -25,7 +25,7 @@ describe('ctx.href', function(){
   })
 
   it('should work with `GET http://example.com/foo`', function(done){
-    const app = koa()
+    const app = new Koa()
     app.use(function* (){
       this.body = this.href
     })

test/request/origin.js

@@ -3,7 +3,7 @@
 
 const Stream = require('stream');
 const http = require('http');
-const koa = require('../../');
+const Koa = require('../../');
 const context = require('../helpers/context');
 
 describe('ctx.origin', function(){

test/response/attachment.js

@@ -3,7 +3,7 @@
 
 const context = require('../helpers/context');
 const request = require('supertest');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('ctx.attachment([filename])', function(){
   describe('when given a filename', function(){
@@ -32,7 +32,7 @@ describe('ctx.attachment([filename])', function(){
     })
 
     it('should work with http client', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function* (next){
         this.attachment('path/to/include-no-ascii-char-中文名-ok.json')

test/response/status.js

@@ -5,7 +5,7 @@ const response = require('../helpers/context').response;
 const request = require('supertest');
 const statuses = require('statuses');
 const assert = require('assert');
-const koa = require('../..');
+const Koa = require('../..');
 
 describe('res.status=', function(){
   describe('when a status code', function(){
@@ -60,7 +60,7 @@ describe('res.status=', function(){
 
   function strip(status) {
     it('should strip content related header fields', function(done){
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.body = { foo: 'bar' };
@@ -86,7 +86,7 @@ describe('res.status=', function(){
     })
 
     it('should strip content releated header fields after status set', function(done) {
-      const app = koa();
+      const app = new Koa();
 
       app.use(function *(){
         this.status = status;