DurationFormat: Add tests for durations with style: "digital", `hou…

…rsDisplay: "auto"` and zero hours

test/intl402/DurationFormat/prototype/format/digital-style-with-hours-display-auto-with-zero-hour.js

@@ -0,0 +1,36 @@
+// Copyright (C) 2024 Sosuke Suzuki. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-Intl.DurationFormat.prototype.format
+description: >
+  The separator isn't printed when style is digital, hoursDisplay is auto and hours value is zero
+locale: [en-US]
+features: [Intl.DurationFormat]
+---*/
+
+const df = new Intl.DurationFormat("en", {
+  style: "digital",
+  hoursDisplay: "auto",
+});
+
+const durations = [
+  // basic zero hours
+  [{ hours: 0, minutes: 0, seconds: 2 }, "00:02"],
+  [{ hours: 0, minutes: 1, seconds: 2 }, "01:02"],
+  [{ days: 1, hours: 0, minutes: 1, seconds: 2 }, "1 day, 01:02"],
+
+  // without hours
+  [{ minutes: 0, seconds: 2 }, "00:02"],
+  [{ minutes: 1, seconds: 2 }, "01:02"],
+  [{ days: 1,  minutes: 1, seconds: 2 }, "1 day, 01:02"],
+
+  // negative sign
+  [{ hours: 0, minutes: -1, seconds: -2 }, "-01:02"],
+  [{ hours: 0, minutes: -1, seconds: -2 }, "-01:02"],
+  [{ days: -1, hours: 0, minutes: -1, seconds: -2 }, "-1 day, 01:02"],
+];
+
+for (const [duration, expected] of durations) {
+  assert.sameValue(df.format(duration), expected, `Duration is ${duration}`);
+}