feat: live timer since rebuild

test/build-age.test.js

@@ -0,0 +1,62 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import path from "node:path";
+import configureEleventy from "../eleventy.config.js";
+import { formatBuildAge } from "../src/assets/js/build-timer.js";
+
+test("Build age: formats elapsed time as a compact live footer value", () => {
+  assert.equal(
+    formatBuildAge("2026-10-20T12:00:00.000Z", "2026-10-20T12:00:00.000Z"),
+    "0s ago"
+  );
+  assert.equal(
+    formatBuildAge("2026-10-20T12:00:00.000Z", "2026-10-20T12:01:01.000Z"),
+    "1m 1s ago"
+  );
+  assert.equal(
+    formatBuildAge("2026-10-20T12:00:00.000Z", "2026-10-21T14:03:04.000Z"),
+    "1d 2h ago"
+  );
+  assert.equal(
+    formatBuildAge("2026-10-20T12:00:00.000Z", "2026-10-20T11:59:59.000Z"),
+    "0s ago"
+  );
+});
+
+test("Build age: Eleventy exposes one ISO timestamp for each rebuild", () => {
+  const globalData = new Map();
+  const events = new Map();
+  configureEleventy({
+    setUseGitIgnore() {},
+    addPassthroughCopy() {},
+    addPlugin() {},
+    setLibrary() {},
+    addFilter() {},
+    addCollection() {},
+    addGlobalData(name, value) {
+      globalData.set(name, value);
+    },
+    on(name, callback) {
+      events.set(name, callback);
+    },
+    setServerOptions() {}
+  });
+
+  events.get("eleventy.before")();
+  assert.match(
+    globalData.get("buildTimestamp")(),
+    /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/
+  );
+});
+
+test("Build age: footer provides an accessible live timer backed by the build timestamp", () => {
+  const footer = fs.readFileSync(path.resolve("src/_includes/partials/footer.njk"), "utf-8");
+  const baseLayout = fs.readFileSync(path.resolve("src/_includes/layouts/base.njk"), "utf-8");
+
+  assert.match(
+    footer,
+    /<time id="build-age" data-build-timestamp="{{ buildTimestamp }}" aria-live="polite">REBUILT: INITIALIZING<\/time>/
+  );
+  assert.match(baseLayout, /<script type="module" src="\/assets\/js\/build-timer\.js"><\/script>/);
+});

test/linked-articles.test.js

@@ -95,6 +95,8 @@ test("Linked articles: the Eleventy posts collection rejects invalid frontmatter
     addCollection(name, callback) {
       collections.set(name, callback);
     },
+    addGlobalData() {},
+    on() {},
     setServerOptions() {}
   });