mock date for spec

in the time calc there may be subtle drift if our date-fns parsing "copies" certain elements from the runtime clock when they're not defined in our date strings

package.json

@@ -22,6 +22,7 @@
   "dependencies": {
     "d3-node": "^3.0.0",
     "date-fns": "^3.3.0",
+    "mockdate": "^3.0.5",
     "point-at-length": "^1.1.0",
     "reading-time": "^1.5.0",
     "vitest": "^1.2.1"

site/src/lib/server/timeline.test.ts

@@ -1,10 +1,17 @@
-import { expect, test } from "vitest";
+import MockDate from "mockdate";
+import { afterAll, beforeAll, expect, test } from "vitest";
 import { getTimeline } from "./timeline";
 import { getSvgDomain } from "./svg";
 import { getEnhancedPosts } from "./posts";
 import dataFixture from "./__fixtures__/data.json";
 
 test("timeline datamodel integration", () => {
+  beforeAll(() => {
+    MockDate.set(new Date(2023, 12, 31, 23, 0, 0, 0));
+  });
+
+  afterAll(() => MockDate.reset());
+
   const posts = getEnhancedPosts(
     require("../../content/enabler/talbroda.json").posts
   );