feat: enhance plugin API support and update tests for new compile behavior

Author: bjohansebas

test/e2e/__snapshots__/api.test.js.snap.webpack5

@@ -165,3 +165,13 @@ exports[`API latest async API should work with callback API: console messages 1`
 `;
 
 exports[`API latest async API should work with callback API: page errors 1`] = `[]`;
+
+exports[`API should work with plugin API: console messages 1`] = `
+[
+  "[webpack-dev-server] Server started: Hot Module Replacement enabled, Live Reloading enabled, Progress disabled, Overlay enabled.",
+  "[HMR] Waiting for update signal from WDS...",
+  "Hey.",
+]
+`;
+
+exports[`API should work with plugin API: page errors 1`] = `[]`;

test/e2e/api.test.js

@@ -15,7 +15,9 @@ describe("API", () => {
     const server = new Server({ port });
 
     server.apply(compiler);
-    await compile(compiler);
+
+    // Use compile helper which waits for the server to be ready
+    const { watching } = await compile(compiler, port);
 
     const { page, browser } = await runBrowser();
 
@@ -40,7 +42,7 @@ describe("API", () => {
     expect(pageErrors).toMatchSnapshot("page errors");
 
     await browser.close();
-    compiler.watching.close();
+    watching.close();
   });
 
   describe("WEBPACK_SERVE environment variable", () => {

test/helpers/compile.js

@@ -1,12 +1,44 @@
 "use strict";
 
-module.exports = (compiler) =>
+// Helper function to check if server is ready using fetch
+const waitForServer = async (port, timeout = 10000) => {
+  const start = Date.now();
+
+  while (Date.now() - start < timeout) {
+    try {
+      // eslint-disable-next-line n/no-unsupported-features/node-builtins
+      await fetch(`http://127.0.0.1:${port}/`);
+      return; // Server is ready
+    } catch {
+      // Server not ready yet, wait and retry
+      await new Promise((resolve) => {
+        setTimeout(resolve, 100);
+      });
+    }
+  }
+
+  throw new Error(`Server on port ${port} not ready after ${timeout}ms`);
+};
+
+module.exports = (compiler, port = null) =>
   new Promise((resolve, reject) => {
-    compiler.run((error, stats) => {
+    const watching = compiler.watch({}, async (error, stats) => {
       if (error) {
+        watching.close();
         return reject(error);
       }
 
-      return resolve(stats);
+      // If a port is provided, wait for the server to be ready
+      if (port) {
+        try {
+          await waitForServer(port);
+        } catch (err) {
+          watching.close();
+          return reject(err);
+        }
+      }
+
+      // Return both stats and watching for caller to manage
+      resolve({ stats, watching });
     });
   });