add testing to status-page functions (#12)

status-page/src/lib/header.test.ts

@@ -0,0 +1,27 @@
+import { describe, it, expect, afterAll } from 'vitest';
+import { formatAbsoluteTime } from './header.js';
+
+describe('formatAbsoluteTime', () => {
+  const origTZ = process.env.TZ;
+
+  afterAll(() => {
+    process.env.TZ = origTZ;
+  });
+
+  it('formats timestamp in UTC', () => {
+    process.env.TZ = 'UTC';
+    // 1704067200 = 2024-01-01 00:00:00 UTC
+    const result = formatAbsoluteTime(1704067200);
+    expect(result).toContain('Jan');
+    expect(result).toContain('1,');
+    expect(result).toContain('00:00');
+  });
+
+  it('returns month abbreviation in English', () => {
+    process.env.TZ = 'UTC';
+    // 1719792000 = 2024-07-01 00:00:00 UTC
+    const result = formatAbsoluteTime(1719792000);
+    expect(result).toContain('Jul');
+    expect(result).toContain('1,');
+  });
+});