test: add cache filter regression coverage

test/filter.test.js

@@ -0,0 +1,46 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { filterCaches } from "../src/filter.js";
+
+const now = Date.UTC(2026, 5, 20);
+const day = 24 * 60 * 60_000;
+
+const caches = [
+  { path: "node-small", type: "node", bytes: 100, modifiedAtMs: now - day },
+  { path: "node-large", type: "node", bytes: 500, modifiedAtMs: now - 7 * day },
+  { path: "python-large", type: "python", bytes: 500, modifiedAtMs: now - 14 * day },
+];
+
+test("returns every cache when no filters are active", () => {
+  assert.deepEqual(filterCaches(caches, {}, now), caches);
+});
+
+test("combines type, size, and age filters", () => {
+  const result = filterCaches(
+    caches,
+    { minSize: 500, olderThan: 7 * day, types: new Set(["node"]) },
+    now,
+  );
+
+  assert.deepEqual(result.map((cache) => cache.path), ["node-large"]);
+});
+
+test("includes entries exactly on size and age boundaries", () => {
+  const result = filterCaches(
+    caches,
+    { minSize: 500, olderThan: 14 * day },
+    now,
+  );
+
+  assert.deepEqual(result.map((cache) => cache.path), ["python-large"]);
+});
+
+test("supports selecting multiple cache types", () => {
+  const result = filterCaches(
+    caches,
+    { types: new Set(["node", "python"]) },
+    now,
+  );
+
+  assert.deepEqual(result, caches);
+});