test: align envelope timestamp expectations (#1329) (thanks @dlauer)

test/helpers/envelope-timestamp.ts

@@ -1,5 +1,17 @@
-export function formatLocalEnvelopeTimestamp(date: Date): string {
+type EnvelopeTimestampZone = string;
+
+function formatUtcTimestamp(date: Date): string {
+  const yyyy = String(date.getUTCFullYear()).padStart(4, "0");
+  const mm = String(date.getUTCMonth() + 1).padStart(2, "0");
+  const dd = String(date.getUTCDate()).padStart(2, "0");
+  const hh = String(date.getUTCHours()).padStart(2, "0");
+  const min = String(date.getUTCMinutes()).padStart(2, "0");
+  return `${yyyy}-${mm}-${dd}T${hh}:${min}Z`;
+}
+
+function formatZonedTimestamp(date: Date, timeZone?: string): string {
   const parts = new Intl.DateTimeFormat("en-US", {
+    timeZone,
     year: "numeric",
     month: "2-digit",
     day: "2-digit",
@@ -27,6 +39,17 @@ export function formatLocalEnvelopeTimestamp(date: Date): string {
   return `${yyyy}-${mm}-${dd} ${hh}:${min}${tz ? ` ${tz}` : ""}`;
 }
 
+export function formatEnvelopeTimestamp(date: Date, zone: EnvelopeTimestampZone = "utc"): string {
+  const normalized = zone.trim().toLowerCase();
+  if (normalized === "utc" || normalized === "gmt") return formatUtcTimestamp(date);
+  if (normalized === "local" || normalized === "host") return formatZonedTimestamp(date);
+  return formatZonedTimestamp(date, zone);
+}
+
+export function formatLocalEnvelopeTimestamp(date: Date): string {
+  return formatEnvelopeTimestamp(date, "local");
+}
+
 export function escapeRegExp(value: string): string {
   return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
 }