fix(server): set port before instantiating server

bin/webpack-dev-server.js

@@ -15,7 +15,6 @@ const setupExitSignals = require('../lib/utils/setupExitSignals');
 const colors = require('../lib/utils/colors');
 const processOptions = require('../lib/utils/processOptions');
 const createLogger = require('../lib/utils/createLogger');
-const findPort = require('../lib/utils/findPort');
 const getVersions = require('../lib/utils/getVersions');
 const options = require('./options');
 
@@ -148,18 +147,11 @@ function startDevServer(config, options) {
       });
     });
   } else {
-    findPort(options.port)
-      .then((port) => {
-        options.port = port;
-        server.listen(options.port, options.host, (err) => {
-          if (err) {
-            throw err;
-          }
-        });
-      })
-      .catch((err) => {
+    server.listen(options.port, options.host, (err) => {
+      if (err) {
         throw err;
-      });
+      }
+    });
   }
 }
 

lib/utils/processOptions.js

@@ -2,6 +2,7 @@
 
 const createConfig = require('./createConfig');
 const defaultPort = require('./defaultPort');
+const findPort = require('./findPort');
 
 function processOptions(config, argv, callback) {
   // processOptions {Promise}
@@ -23,7 +24,21 @@ function processOptions(config, argv, callback) {
   // we should use portfinder.
   const options = createConfig(config, argv, { port: defaultPort });
 
-  callback(config, options);
+  if (options.socket) {
+    callback(config, options);
+  } else {
+    findPort(options.port)
+      .then((port) => {
+        options.port = port;
+        callback(config, options);
+      })
+      .catch((err) => {
+        // eslint-disable-next-line no-console
+        console.error(err.stack || err);
+        // eslint-disable-next-line no-process-exit
+        process.exit(1);
+      });
+  }
 }
 
 module.exports = processOptions;

test/cli/cli.test.js

@@ -78,13 +78,22 @@ describe('CLI', () => {
     testBin('--sockPath /mysockPath')
       .then((output) => {
         expect(
-          output.stdout.includes('http://localhost&sockPath=/mysockPath')
+          /http:\/\/localhost:[0-9]+&sockPath=\/mysockPath/.test(output.stdout)
         ).toEqual(true);
         done();
       })
       .catch(done);
   });
 
+  it('unspecified port', (done) => {
+    testBin('')
+      .then((output) => {
+        expect(/http:\/\/localhost:[0-9]+/.test(output.stdout)).toEqual(true);
+        done();
+      })
+      .catch(done);
+  });
+
   it('--color', (done) => {
     testBin('--color')
       .then((output) => {