feat: support entry descriptor (closes #2453)

lib/utils/addEntries.js

@@ -68,7 +68,15 @@ function addEntries(config, options, server) {
 
         Object.keys(originalEntry).forEach((key) => {
           // entry[key] should be a string here
-          clone[key] = prependEntry(originalEntry[key], additionalEntries);
+          const entryDescription = originalEntry[key];
+          if (typeof entryDescription === 'object' && entryDescription.import) {
+            clone[key] = {
+              ...entryDescription,
+              import: prependEntry(entryDescription.import, additionalEntries),
+            };
+          } else {
+            clone[key] = prependEntry(entryDescription, additionalEntries);
+          }
         });
 
         return clone;

test/fixtures/entry-as-descriptor/foo.js

@@ -0,0 +1,3 @@
+'use strict';
+
+console.log('i am foo!');

test/fixtures/entry-as-descriptor/webpack.config.js

@@ -0,0 +1,24 @@
+'use strict';
+
+module.exports = {
+  mode: 'development',
+  context: __dirname,
+  entry: {
+    main: {
+      import: './foo.js',
+    },
+  },
+  plugins: [
+    {
+      apply(compiler) {
+        compiler.hooks.done.tap('webpack-dev-server', (stats) => {
+          let exitCode = 0;
+          if (stats.hasErrors()) {
+            exitCode = 1;
+          }
+          setTimeout(() => process.exit(exitCode));
+        });
+      },
+    },
+  ],
+};

test/server/utils/addEntries.test.js

@@ -5,6 +5,7 @@ const webpack = require('webpack');
 const addEntries = require('../../../lib/utils/addEntries');
 const config = require('./../../fixtures/simple-config/webpack.config');
 const configEntryAsFunction = require('./../../fixtures/entry-as-function/webpack.config');
+const configEntryAsDescriptor = require('./../../fixtures/entry-as-descriptor/webpack.config');
 
 const normalize = (entry) => entry.split(path.sep).join('/');
 
@@ -290,6 +291,17 @@ describe('addEntries util', () => {
     expect(typeof webpackOptions.entry === 'function').toBe(true);
   });
 
+  it('should supports entry as descriptor', () => {
+    const webpackOptions = Object.assign({}, configEntryAsDescriptor);
+    const devServerOptions = {};
+
+    addEntries(webpackOptions, devServerOptions);
+
+    expect(typeof webpackOptions.entry === 'object').toBe(true);
+    expect(typeof webpackOptions.entry.main === 'object').toBe(true);
+    expect(Array.isArray(webpackOptions.entry.main.import)).toBe(true);
+  });
+
   it('should only prepends devServer entry points to web targets by default', () => {
     const webpackOptions = [
       Object.assign({}, config),