feat: onListening option

lib/Server.js

@@ -434,6 +434,8 @@ class Server {
   }
 
   setupBeforeFeature() {
+    // Todo rename onBeforeSetupMiddleware in next major release
+    // Todo pass only `this` argument
     this.options.before(this.app, this, this.compiler);
   }
 
@@ -442,6 +444,8 @@ class Server {
   }
 
   setupAfterFeature() {
+    // Todo rename onAfterSetupMiddleware in next major release
+    // Todo pass only `this` argument
     this.options.after(this.app, this, this.compiler);
   }
 
@@ -757,6 +761,10 @@ class Server {
       if (fn) {
         fn.call(this.listeningApp, err);
       }
+
+      if (typeof this.options.onListening === 'function') {
+        this.options.onListening(this);
+      }
     });
   }
 

lib/options.json

@@ -195,6 +195,9 @@
     "noInfo": {
       "type": "boolean"
     },
+    "onListening": {
+      "instanceof": "Function"
+    },
     "open": {
       "anyOf": [
         {
@@ -402,6 +405,7 @@
       "logTime": "should be {Boolean} (https://github.com/webpack/webpack-dev-middleware#logtime)",
       "mimeTypes": "should be {Object} (https://webpack.js.org/configuration/dev-server/#devservermimetypes-)",
       "noInfo": "should be {Boolean} (https://webpack.js.org/configuration/dev-server/#devservernoinfo-)",
+      "onListening": "should be {Function} (https://webpack.js.org/configuration/dev-server/#onlistening)",
       "open": "should be {String|Boolean} (https://webpack.js.org/configuration/dev-server/#devserveropen)",
       "openPage": "should be {String} (https://webpack.js.org/configuration/dev-server/#devserveropenpage)",
       "overlay": "should be {Boolean|Object} (https://webpack.js.org/configuration/dev-server/#devserveroverlay)",

test/CreateConfig.test.js

@@ -967,4 +967,16 @@ describe('createConfig', () => {
     ).toMatchSnapshot();
     expect(webpackConfigNoStats).toMatchSnapshot();
   });
+
+  it('onListening option', () => {
+    const config = createConfig(
+      Object.assign({}, webpackConfig, {
+        devServer: { onListening: () => {} },
+      }),
+      argv,
+      { port: 8080 }
+    );
+
+    expect(config).toMatchSnapshot();
+  });
 });

test/__snapshots__/CreateConfig.test.js.snap

@@ -740,6 +740,21 @@ Object {
 }
 `;
 
+exports[`createConfig onListening option 1`] = `
+Object {
+  "hot": true,
+  "hotOnly": false,
+  "noInfo": true,
+  "onListening": [Function],
+  "port": 8080,
+  "publicPath": "/",
+  "stats": Object {
+    "cached": false,
+    "cachedAssets": false,
+  },
+}
+`;
+
 exports[`createConfig open option (boolean) (in devServer config) 1`] = `
 Object {
   "hot": true,

test/onListening.test.js

@@ -0,0 +1,30 @@
+'use strict';
+
+const testServer = require('./helpers/test-server');
+const config = require('./fixtures/simple-config/webpack.config');
+
+describe('Before And After options', () => {
+  let onListeningIsRunning = false;
+
+  beforeAll((done) => {
+    testServer.start(
+      config,
+      {
+        onListening: (devServer) => {
+          if (!devServer) {
+            throw new Error('webpack-dev-server is not defined');
+          }
+
+          onListeningIsRunning = true;
+        },
+      },
+      done
+    );
+  });
+
+  afterAll(testServer.close);
+
+  it('should handle before route', () => {
+    expect(onListeningIsRunning).toBe(true);
+  });
+});

test/options.test.js

@@ -244,6 +244,10 @@ describe('options', () => {
         success: [true],
         failure: [''],
       },
+      onListening: {
+        success: [() => {}],
+        failure: [''],
+      },
       open: {
         success: [true, ''],
         failure: [{}],