add basic unit test

jest.config.js

@@ -0,0 +1,11 @@
+const { createDefaultPreset } = require("ts-jest");
+
+const tsJestTransformCfg = createDefaultPreset().transform;
+
+/** @type {import("jest").Config} **/
+module.exports = {
+  testEnvironment: "node",
+  transform: {
+    ...tsJestTransformCfg,
+  },
+};

mise.toml

@@ -3,3 +3,6 @@ node = "24"
 
 [tasks.build]
 run = "npx rollup -c"
+
+[tasks.test]
+run = "npx jest"

package.json

@@ -19,7 +19,10 @@
   "devDependencies": {
     "@rollup/plugin-terser": "^0.4.4",
     "@rollup/plugin-typescript": "^12.3.0",
+    "@types/jest": "^30.0.0",
+    "jest": "^30.2.0",
     "rollup": "^4.57.1",
+    "ts-jest": "^29.4.6",
     "tslib": "^2.8.1",
     "typescript": "^5.9.3"
   }

src/index.test.ts

@@ -0,0 +1,24 @@
+import { AsyncTaskQueue } from "./index";
+
+test("example evaluates correctly", async () => {
+  const q = new AsyncTaskQueue<number>(
+    async (nums: number[]) => {/* no-op */},
+  )
+    // Handler will receive up to 4 items per batch.
+    .batchSize(4)
+    // Handler will be called at most once per 100 milliseconds.
+    .throttleMs(100);
+
+  // Add items to the queue.
+  for (let n = 0; n < 1000; n++) {
+    q.push(n);
+  }
+
+  await new Promise((resolve) => setTimeout(resolve, 4000));
+
+  expect(q.size()).toBeLessThan(900);
+  expect(q.size()).toBeGreaterThan(800);
+
+  q.drain();
+  expect(q.size()).toEqual(0);
+});

src/index.ts

@@ -102,7 +102,7 @@ export class AsyncTaskQueue<T> {
         : Promise.resolve();
 
       const items = this._queue.splice(0, this._batchSize);
-      await this._handler(items).catch(this._error_handler);
+      await this._handler(items).catch(this._errorHandler);
 
       await throttleTimeout;
     }