feat: harden analytics dashboard

lib/query-cache.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, test } from "bun:test";
+import { createQueryCache } from "./query-cache";
+
+describe("query cache", () => {
+  test("returns cached values inside TTL", async () => {
+    let now = 1_000;
+    const cache = createQueryCache({ ttlMs: 100, maxEntries: 10, now: () => now });
+    let calls = 0;
+
+    const first = await cache.cached("key", async () => {
+      calls += 1;
+      return { value: "first" };
+    });
+    now += 50;
+    const second = await cache.cached("key", async () => {
+      calls += 1;
+      return { value: "second" };
+    });
+
+    expect(first).toEqual({ value: "first" });
+    expect(second).toEqual({ value: "first" });
+    expect(calls).toBe(1);
+  });
+
+  test("refreshes expired values", async () => {
+    let now = 1_000;
+    const cache = createQueryCache({ ttlMs: 100, maxEntries: 10, now: () => now });
+
+    await cache.cached("key", async () => "first");
+    now += 101;
+    const second = await cache.cached("key", async () => "second");
+
+    expect(second).toBe("second");
+  });
+
+  test("evicts oldest entries beyond max size", async () => {
+    const cache = createQueryCache({ ttlMs: 1_000, maxEntries: 2, now: () => 1_000 });
+    let calls = 0;
+
+    await cache.cached("a", async () => "a");
+    await cache.cached("b", async () => "b");
+    await cache.cached("c", async () => "c");
+    const value = await cache.cached("a", async () => {
+      calls += 1;
+      return "new-a";
+    });
+
+    expect(value).toBe("new-a");
+    expect(calls).toBe(1);
+  });
+});