feat: deprecate setup in favor of before and after hooks

fixes webpack#869

lib/Server.js

@@ -323,7 +323,9 @@ function Server(compiler, options) {
 
     middleware: () => {
       // include our middleware to ensure it is able to handle '/index.html' request after redirect
+      if (typeof options.before === 'function') { options.before(app, this); }
       app.use(this.middleware);
+      if (typeof options.after === 'function') { options.after(app, this); }
     },
 
     headers: () => {
@@ -335,6 +337,8 @@ function Server(compiler, options) {
     },
 
     setup: () => {
+      log('Using "setup" is deprecated and will be removed in the next major version. Please use the "before" and "after" hooks instead.');
+      log('If "setup" was working fine for you until now, simply replace it with "before"');
       if (typeof options.setup === 'function') { options.setup(app, this); }
     }
   };

lib/optionsSchema.json

@@ -274,6 +274,14 @@
       "description": "Exposes the Express server to add custom middleware or routes.",
       "instanceof": "Function"
     },
+    "before": {
+      "description": "Exposes the Express server to add custom middleware or routes before webpack-dev-middleware will be added.",
+      "instanceof": "Function"
+    },
+    "after": {
+      "description": "Exposes the Express server to add custom middleware or routes after webpack-dev-middleware got added.",
+      "instanceof": "Function"
+    },
     "stats": {
       "description": "Decides what bundle information is displayed.",
       "anyOf": [

test/Validation.test.js

@@ -51,7 +51,7 @@ describe('Validation', () => {
       '   object { hot?, hotOnly?, lazy?, bonjour?, host?, allowedHosts?, filename?, publicPath?, port?, socket?, ' +
       'watchOptions?, headers?, clientLogLevel?, overlay?, progress?, key?, cert?, ca?, pfx?, pfxPassphrase?, requestCert?, ' +
       'inline?, disableHostCheck?, public?, https?, contentBase?, watchContentBase?, open?, useLocalIp?, openPage?, features?, ' +
-      'compress?, proxy?, historyApiFallback?, staticOptions?, setup?, stats?, reporter?, ' +
+      'compress?, proxy?, historyApiFallback?, staticOptions?, setup?, before?, after? stats?, reporter?, ' +
       'noInfo?, quiet?, serverSideRender?, index?, log?, warn? }'
     ]
   }];