Add support for custom statuses

lib/application.js

@@ -46,6 +46,18 @@ module.exports = class Application extends Emitter {
     this.context = Object.create(context);
     this.request = Object.create(request);
     this.response = Object.create(response);
+    this.customStatuses = {};
+  }
+
+  /**
+   * Add custom status code
+   * @param {Number} code
+   * @param {String} description
+   * @api public
+   */
+
+  addStatus(code, description) {
+    this.customStatuses[code] = description;
   }
 
   /**
@@ -166,6 +178,7 @@ module.exports = class Application extends Emitter {
     request.ctx = response.ctx = context;
     request.response = response;
     response.request = request;
+    response.customStatuses = this.customStatuses;
     context.originalUrl = request.originalUrl = req.url;
     context.cookies = new Cookies(req, res, {
       keys: this.keys,

lib/response.js

@@ -81,11 +81,11 @@ module.exports = {
 
   set status(code) {
     assert('number' == typeof code, 'status code must be a number');
-    assert(statuses[code], `invalid status code: ${code}`);
+    assert(statuses[code] || this.customStatuses[code], `invalid status code: ${code}`);
     assert(!this.res.headersSent, 'headers have already been sent');
     this._explicitStatus = true;
     this.res.statusCode = code;
-    if (this.req.httpVersionMajor < 2) this.res.statusMessage = statuses[code];
+    if (this.req.httpVersionMajor < 2) this.res.statusMessage = statuses[code] || this.customStatuses[code];
     if (this.body && statuses.empty[code]) this.body = null;
   },
 

test/application/respond.js

@@ -315,7 +315,7 @@ describe('app.respond', () => {
     describe('with custom status=700', () => {
       it('should respond with the associated status message', async () => {
         const app = new Koa();
-        statuses['700'] = 'custom status';
+        app.addStatus(700, 'custom status');
 
         app.use(ctx => {
           ctx.status = 700;