DurationFormat basic format tests (#3604)

test/intl402/DurationFormat/prototype/format/basic-format-en.js

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+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-Intl.DurationFormat.prototype.format
+description: Test if format method formats duration correctly
+locale: [en-US]
+features: [Intl.DurationFormat]
+---*/
+
+const duration = {
+  years: 1,
+  months: 2,
+  weeks: 3,
+  days: 3,
+  hours: 4,
+  minutes: 5,
+  seconds: 6,
+  milliseconds: 7,
+  microseconds: 8,
+  nanoseconds: 9,
+};
+
+const df = new Intl.DurationFormat('en');
+
+assert.sameValue(df.format(duration), "1 year, 2 months, 3 weeks, 3 days, 4 hours, 5 minutes, 6 seconds, 7 milliseconds, 8 microseconds, and 9 nanoseconds");

test/intl402/DurationFormat/prototype/format/style-options-en.js

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+// Copyright 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-Intl.DurationFormat.prototype.format
+description: Test if format method formats duration correctly with different "style" arguments
+locale: [en-US]
+features: [Intl.DurationFormat]
+---*/
+
+const testData = {
+  "long" : "1 year, 2 months, 3 weeks, 3 days, 4 hours, 5 minutes, 6 seconds, 7 milliseconds, 8 microseconds, and 9 nanoseconds",
+  "short": "1 yr, 2 mths, 3 wks, 3 days, 4 hr, 5 min, 6 sec, 7 ms, 8 μs, and 9 ns",
+  "narrow":"1y, 2m, 3w, 3d, 4h, 5m, 6s, 7ms, 8μs, and 9ns",
+  "digital":"1y, 2m, 3w, 3d, and 4:05:06.007",
+}
+
+const duration = {
+  years: 1,
+  months: 2,
+  weeks: 3,
+  days: 3,
+  hours: 4,
+  minutes: 5,
+  seconds: 6,
+  milliseconds: 7,
+  microseconds: 8,
+  nanoseconds: 9,
+};
+
+
+for (const style in testData) {
+   const df = new Intl.DurationFormat("en", {style});
+   const expected = testData[style];
+   assert.sameValue(df.format(duration), expected, `Assert DurationFormat format output using ${style} style option`);
+}
+