feat(server): serverMode 'ws' option (#2082)

* feat(server): server mode ws string option

* test(server): rearrange bad host test

* test(server): added mock server implementation tests

* test(server): remove bad host test temporarily

* test(server): re added bad host test

lib/utils/getSocketServerImplementation.js

@@ -9,6 +9,9 @@ function getSocketServerImplementation(options) {
       if (options.serverMode === 'sockjs') {
         // eslint-disable-next-line global-require
         ServerImplementation = require('../servers/SockJSServer');
+      } else if (options.serverMode === 'ws') {
+        // eslint-disable-next-line global-require
+        ServerImplementation = require('../servers/WebsocketServer');
       } else {
         try {
           // eslint-disable-next-line global-require, import/no-dynamic-require
@@ -29,7 +32,7 @@ function getSocketServerImplementation(options) {
 
   if (!serverImplFound) {
     throw new Error(
-      "serverMode must be a string denoting a default implementation (e.g. 'sockjs'), a full path to " +
+      "serverMode must be a string denoting a default implementation (e.g. 'sockjs', 'ws'), a full path to " +
         'a JS file which exports a class extending BaseServer (webpack-dev-server/lib/servers/BaseServer) ' +
         'via require.resolve(...), or the class itself which extends BaseServer'
     );

test/server/__snapshots__/serverMode-option.test.js.snap

@@ -1,17 +1,91 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`serverMode option with a bad host header results in an error 1`] = `
+exports[`serverMode option passed to server with a bad host header results in an error 1`] = `
 Array [
   "open",
   "{\\"type\\":\\"error\\",\\"data\\":\\"Invalid Host/Origin header\\"}",
   "close",
 ]
 `;
 
-exports[`serverMode option without a header results in an error 1`] = `
+exports[`serverMode option passed to server without a header results in an error 1`] = `
 Array [
   "open",
   "{\\"type\\":\\"error\\",\\"data\\":\\"Invalid Host/Origin header\\"}",
   "close",
 ]
 `;
+
+exports[`serverMode option server should close client with bad headers 1`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`serverMode option server should close client with bad headers 2`] = `
+Array [
+  Array [
+    Object {
+      "foo": "bar",
+    },
+    "{\\"type\\":\\"error\\",\\"data\\":\\"Invalid Host/Origin header\\"}",
+  ],
+]
+`;
+
+exports[`serverMode option server should close client with bad headers 3`] = `
+Array [
+  Array [
+    Object {
+      "foo": "bar",
+    },
+  ],
+]
+`;
+
+exports[`serverMode option server should use server implementation correctly 1`] = `
+Array [
+  Object {
+    "foo": "bar",
+  },
+]
+`;
+
+exports[`serverMode option server should use server implementation correctly 2`] = `
+Array [
+  Array [
+    [Function],
+  ],
+]
+`;
+
+exports[`serverMode option server should use server implementation correctly 3`] = `
+Array [
+  Object {
+    "foo": "bar",
+  },
+  "{\\"type\\":\\"liveReload\\"}",
+]
+`;
+
+exports[`serverMode option server should use server implementation correctly 4`] = `
+Array [
+  Object {
+    "foo": "bar",
+  },
+  "{\\"type\\":\\"ok\\"}",
+]
+`;
+
+exports[`serverMode option server should use server implementation correctly 5`] = `
+Array [
+  Array [
+    Object {
+      "foo": "bar",
+    },
+    [Function],
+  ],
+]
+`;