test: add test for overlay runtime error at initial load

Author: kehach07

client-src/index.js

@@ -45,6 +45,7 @@ import sendMessage from "./utils/sendMessage.js";
  * @property {boolean} isUnloading true when unloaded, otherwise false
  * @property {string} currentHash current hash
  * @property {string=} previousHash previous hash
+ * @property {boolean} hasRuntimeError true when a runtime error occurred
  */
 
 /**

test/e2e/overlay-initial-runtime-error.test.js

@@ -0,0 +1,49 @@
+"use strict";
+
+const path = require("node:path");
+const puppeteer = require("puppeteer");
+const webpack = require("webpack");
+const WebpackDevServer = require("../../lib/Server");
+
+describe("overlay runtime error", () => {
+  let browser;
+  let page;
+  let server;
+
+  beforeAll(async () => {
+    const config = {
+      mode: "development",
+      entry: path.resolve(__dirname, "../fixtures/overlay-runtime-error.js"),
+    };
+
+    const compiler = webpack(config);
+
+    server = new WebpackDevServer(
+      {
+        port: 8081,
+        client: {
+          overlay: true,
+        },
+      },
+      compiler,
+    );
+
+    await server.start();
+
+    browser = await puppeteer.launch();
+    page = await browser.newPage();
+  });
+
+  afterAll(async () => {
+    await browser.close();
+    await server.stop();
+  });
+
+  it("should keep overlay visible on runtime error during initial load", async () => {
+    await page.goto("http://localhost:8081");
+
+    const overlay = await page.$("webpack-dev-server-client-overlay");
+
+    expect(overlay).not.toBeNull();
+  });
+});

test/fixtures/overlay-runtime-error.js

@@ -0,0 +1 @@
+throw new Error("Initial runtime error");