feat: Implement caching and rate limiting for API requests

test/limits.test.js

@@ -0,0 +1,52 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { rateLimit, semaphore } from "../server/limits.js";
+
+test("Импорт: не больше двух разборов сразу, лишние ждут или получают 429", async () => {
+  const run = semaphore({ limit: 2, queue: 1, message: "Занято" });
+  let active = 0,
+    peak = 0;
+  const release = [];
+  const task = () =>
+    run(async () => {
+      peak = Math.max(peak, ++active);
+      await new Promise((resolve) => release.push(resolve));
+      active--;
+    });
+  const running = [task(), task(), task()];
+  await assert.rejects(task(), (e) => e.status === 429 && e.message === "Занято");
+  // Each finished task hands its slot to the one waiting.
+  while (release.length) {
+    release.shift()();
+    await new Promise((resolve) => setImmediate(resolve));
+  }
+  await Promise.all(running);
+  assert.equal(peak, 2);
+  // All slots are free again.
+  assert.equal(await run(async () => "ok"), "ok");
+});
+
+test("Импорт: лимит запросов считается по адресу клиента", () => {
+  const limit = rateLimit({ max: 2, windowMs: 60_000, message: "Подождите" });
+  const call = (ip) => {
+    let status = 200,
+      body = null,
+      passed = false;
+    const res = {
+      set() {},
+      status(code) {
+        status = code;
+        return this;
+      },
+      json(value) {
+        body = value;
+      },
+    };
+    limit({ ip }, res, () => (passed = true));
+    return { status, body, passed };
+  };
+  assert.ok(call("10.0.0.1").passed);
+  assert.ok(call("10.0.0.1").passed);
+  assert.deepEqual(call("10.0.0.1"), { status: 429, body: { error: "Подождите" }, passed: false });
+  assert.ok(call("10.0.0.2").passed);
+});