refactor: migrate to node:test and setup jsdom environment

.github/workflows/nodejs.yml

@@ -106,7 +106,7 @@ jobs:
           cp -R tmp-client client
 
       - name: Run tests for webpack version ${{ matrix.webpack-version }}
-        run: npm run test:coverage -- --ci --shard=${{ matrix.shard }}
+        run: npm run test:coverage -- --test-shard=${{ matrix.shard }}
 
       - name: Submit coverage data to codecov
         uses: codecov/codecov-action@v5

client-src/socket.js

@@ -6,10 +6,13 @@ import { log } from "./utils/log.js";
 /** @typedef {import("./index.js").EXPECTED_ANY} EXPECTED_ANY */
 /** @typedef {WebSocketClient} */
 
-// this WebsocketClient is here as a default fallback, in case the client is not injected
-/** @type {CommunicationClientConstructor} */
-const Client =
-  typeof __webpack_dev_server_client__ !== "undefined"
+/**
+ * Resolves the client constructor at call time so callers (and tests) can
+ * override the global without relying on module-load ordering.
+ * @returns {CommunicationClientConstructor} client constructor
+ */
+function resolveClient() {
+  return typeof __webpack_dev_server_client__ !== "undefined"
     ? typeof (
         /** @type {{ default: CommunicationClientConstructor }} */
         (__webpack_dev_server_client__).default
@@ -20,6 +23,7 @@ const Client =
           __webpack_dev_server_client__
         )
     : WebSocketClient;
+}
 
 let retries = 0;
 let maxRetries = 10;
@@ -37,8 +41,10 @@ let timeout;
  * @param {string} url url
  * @param {{ [handler: string]: (data?: EXPECTED_ANY, params?: EXPECTED_ANY) => EXPECTED_ANY }} handlers handlers
  * @param {number=} reconnect count of reconnections
+ * @param {CommunicationClientConstructor} Client internal-only override
+ * or tests; defaults to the runtime-resolved client constructor
  */
-function socket(url, handlers, reconnect) {
+function socket(url, handlers, reconnect, Client = resolveClient()) {
   client = new Client(url);
 
   client.onOpen(() => {

client-src/utils/log.js

@@ -1,4 +1,4 @@
-import logger from "../modules/logger/index.js";
+import defaultLogger from "../modules/logger/index.js";
 
 const name = "webpack-dev-server";
 // default level is set on the client side, so it does not need
@@ -8,14 +8,16 @@ const defaultLevel = "info";
 // options new options, merge with old options
 /**
  * @param {false | true | "none" | "error" | "warn" | "info" | "log" | "verbose"} level level
+ * @param {object} logger internal-only override for tests; defaults to the
+ * real webpack runtime logger
  * @returns {void}
  */
-function setLogLevel(level) {
+function setLogLevel(level, logger = defaultLogger) {
   logger.configureDefaultLogger({ level });
 }
 
 setLogLevel(defaultLevel);
 
-const log = logger.getLogger(name);
+const log = defaultLogger.getLogger(name);
 
 export { log, setLogLevel };

eslint.config.mjs

@@ -21,5 +21,23 @@ export default defineConfig([
   {
     files: ["test/**/*"],
     extends: [configs["universal-recommended"]],
+    rules: {
+      // Tests use experimental node:test APIs intentionally
+      // (mock.module, mock.timers, snapshot.*). The package's engines field
+      // is wider than where these are stable, so silence the linter here.
+      "n/no-unsupported-features/node-builtins": "off",
+      // Test callbacks (it/test/subtest arrow functions) don't need JSDoc.
+      "jsdoc/require-jsdoc": "off",
+      // Tests legitimately log diagnostics (retry attempts, etc.).
+      "no-console": "off",
+      // Closure params in reduce/map (`(p, server) => ...`) are conventional.
+      "id-length": "off",
+    },
+  },
+  {
+    files: ["scripts/node-test-setup.mjs"],
+    rules: {
+      "n/no-unsupported-features/node-builtins": "off",
+    },
   },
 ]);