fix(plugin-webpack): preload race condition

packages/plugin/webpack/src/Config.ts

@@ -121,6 +121,10 @@ export interface WebpackPluginRendererConfig {
  entryPoints: WebpackPluginEntryPoint[];
 }
 
+export interface EntryPointPluginConfig {
+ name: string;
+}
+
 export interface WebpackPluginConfig {
  /**
  * The webpack config for your main process

packages/plugin/webpack/src/WebpackPlugin.ts

@@ -14,6 +14,7 @@ import { merge } from 'webpack-merge';
 
 import { WebpackPluginConfig } from './Config';
 import ElectronForgeLoggingPlugin from './util/ElectronForgeLogging';
+import EntryPointPreloadPlugin from './util/EntryPointPreloadPlugin';
 import once from './util/once';
 import WebpackConfigGenerator from './WebpackConfig';
 
@@ -283,25 +284,51 @@ the generated files). Instead, it is ${JSON.stringify(pj.main)}`);
  };
 
  launchRendererDevServers = async (logger: Logger): Promise<void> => {
- const config = await this.configGenerator.getRendererConfig(this.config.renderer.entryPoints);
- if (config.length === 0) {
+ const configs = await this.configGenerator.getRendererConfig(this.config.renderer.entryPoints);
+ if (configs.length === 0) {
  return;
  }
 
- for (const entryConfig of config) {
+ const preloadPlugins: string[] = [];
+ let preloadEntriesWithConfig = 0;
+ for (const entryConfig of configs) {
  if (!entryConfig.plugins) entryConfig.plugins = [];
  entryConfig.plugins.push(new ElectronForgeLoggingPlugin(logger.createTab(`Renderer Target Bundle (${entryConfig.target})`)));
 
+ const filename = entryConfig.output?.filename as string;
+ if (filename?.endsWith('preload.js')) {
+ let name = `entry-point-preload-${entryConfig.target}`;
+ if (preloadPlugins.includes(name)) {
+ name = `${name}-${++preloadEntriesWithConfig}`;
+ }
+ entryConfig.plugins.push(new EntryPointPreloadPlugin({ name }));
+ preloadPlugins.push(name);
+ }
+
  entryConfig.infrastructureLogging = {
  level: 'none',
  };
  entryConfig.stats = 'none';
  }
 
- const compiler = webpack(config);
+ const compiler = webpack(configs);
+
+ const promises = preloadPlugins.map((preloadPlugin) => {
+ return new Promise((resolve, reject) => {
+ compiler.hooks.done.tap(preloadPlugin, (stats) => {
+ if (stats.hasErrors()) {
+ return reject(new Error(`Compilation errors in the preload: ${stats.toString()}`));
+ }
+ return resolve(undefined);
+ });
+ });
+ });
+
  const webpackDevServer = new WebpackDevServer(this.devServerOptions(), compiler);
  await webpackDevServer.start();
+ // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
  this.servers.push(webpackDevServer.server!);
+ await Promise.all(promises);
  };
 
  devServerOptions(): WebpackDevServer.Configuration {

packages/plugin/webpack/src/util/EntryPointPreloadPlugin.ts

@@ -0,0 +1,10 @@
+import { PluginBase } from '@electron-forge/plugin-base';
+
+import { EntryPointPluginConfig } from '../Config';
+
+export default class EntryPointPreloadPlugin extends PluginBase<EntryPointPluginConfig> {
+ name = this.config.name;
+ apply() {
+ // noop
+ }
+}