test: fixed Routes test bug and added server creation helper to await compilation (#1735)

Author: knagaitsev

test/Routes.test.js

@@ -21,7 +21,7 @@ describe('Routes', () => {
 
   describe('without headers', () => {
     beforeAll((done) => {
-      server = helper.start(config, {}, done);
+      server = helper.startAwaitingCompilation(config, {}, done);
       req = request(server.app);
     });
 

test/helper.js

@@ -6,7 +6,9 @@ const Server = require('../lib/Server');
 let server;
 
 module.exports = {
-  start(config, options, done) {
+  // start server, returning the full setup of the server
+  // (both the server and the compiler)
+  startFullSetup(config, options, done) {
     // eslint-disable-next-line no-undefined
     if (options.quiet === undefined) {
       options.quiet = true;
@@ -21,7 +23,28 @@ module.exports = {
       done();
     });
 
-    return server;
+    return {
+      server,
+      compiler,
+    };
+  },
+  startAwaitingCompilation(config, options, done) {
+    let readyCount = 0;
+    const ready = () => {
+      readyCount += 1;
+      if (readyCount === 2) {
+        done();
+      }
+    };
+
+    const fullSetup = this.startFullSetup(config, options, ready);
+    // wait for compilation, since dev server can start before this
+    // https://github.com/webpack/webpack-dev-server/issues/847
+    fullSetup.compiler.hooks.done.tap('done', ready);
+    return fullSetup.server;
+  },
+  start(config, options, done) {
+    return this.startFullSetup(config, options, done).server;
   },
   close(done) {
     if (server) {