// |reftest| skip-if(!this.hasOwnProperty("Intl")||release_or_beta)

// Ensure formatRange() uses a proleptic Gregorian calendar.
// ICU bug: https://unicode-org.atlassian.net/browse/ICU-20705

let dtf = new Intl.DateTimeFormat("en", {timeZone: "UTC"});

// The Gregorian calendar was first introduced in 15 October 1582.
const firstGregorian = new Date("1582-10-15");
assertEq(dtf.formatRange(firstGregorian, firstGregorian), dtf.format(firstGregorian));

// To deal with the ten days' difference between the Julian and the Gregorian calendar, some days
// were skipped, so that 4 October 1582 was followed by 15 October 1582.
const lastJulian = new Date("1582-10-04");
assertEq(dtf.formatRange(lastJulian, lastJulian), dtf.format(lastJulian));

function rangePart(source, parts) {
  return parts.filter(x => x.source === source).map(x => x.value).join("");
}

// Test with non-empty range.
assertEq(rangePart("startRange", dtf.formatRangeToParts(lastJulian, firstGregorian)),
         dtf.format(lastJulian));
assertEq(rangePart("endRange", dtf.formatRangeToParts(lastJulian, firstGregorian)),
         dtf.format(firstGregorian));

if (typeof reportCompare === "function")
  reportCompare(0, 0);