[webpack-dev-server] Add sockWrite method and sockets property (#42986)

types/webpack-dev-server/index.d.ts

@@ -10,6 +10,7 @@
 //                 Billy Le <https://github.com/billy-le>
 //                 Chris Paterson <https://github.com/chrispaterson>
 //                 Piotr Błażejewicz <https://github.com/peterblazejewicz>
+//                 William Artero <https://github.com/wwmoraes>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
@@ -354,6 +355,8 @@ declare module 'webpack' {
 }
 
 declare class WebpackDevServer {
+    sockets: NodeJS.EventEmitter[];
+
     constructor(webpack: webpack.Compiler | webpack.MultiCompiler, config?: WebpackDevServer.Configuration);
 
     static addDevServerEntrypoints(
@@ -367,6 +370,8 @@ declare class WebpackDevServer {
     listen(port: number, callback?: (error?: Error) => void): http.Server;
 
     close(callback?: () => void): void;
+
+    sockWrite(sockets: NodeJS.EventEmitter[], type: string, data?: any): void;
 }
 
 export = WebpackDevServer;

types/webpack-dev-server/webpack-dev-server-tests.ts

@@ -115,6 +115,12 @@ const c6: WebpackDevServer.Configuration = {
 server = new WebpackDevServer(compiler, config);
 server.listen(8080, "localhost", () => { });
 
+// test the socket writer
+server.sockWrite(server.sockets, "type1");
+server.sockWrite(server.sockets, "type2", {message: "OK"});
+
+server.close();
+
 // HTTPS example
 server = new WebpackDevServer(compiler, {
     publicPath: "/assets/",