Temporal: Tests for correct intermediate value in ZonedDateTime diffe…

…rence/rounding These test cases ensure that DST disambiguation does not take place on intermediate values that are not the start or the end of the calculation. See tc39/proposal-temporal#2760
ptomato · Feb 2, 2024 · 40d0a71 · 40d0a71
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diff --git a/test/built-ins/Temporal/Duration/prototype/round/dst-rounding-result.js b/test/built-ins/Temporal/Duration/prototype/round/dst-rounding-result.js
@@ -0,0 +1,45 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-temporal.duration.prototype.round
+description: >
+    Rounding the resulting duration takes the time zone's UTC offset shifts
+    into account
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+// Based on a test case by Adam Shaw
+
+{
+  // Date part of duration lands on skipped DST hour, causing disambiguation
+  const duration = new Temporal.Duration(0, 1, 0, 15, 12);
+  const relativeTo = new Temporal.ZonedDateTime(
+    950868000_000_000_000n /* = 2000-02-18T10Z */,
+    timeZone); /* = 2000-02-18T02-08 in local time */
+
+  TemporalHelpers.assertDuration(duration.round({ smallestUnit: "months", relativeTo }),
+    0, 2, 0, 0, 0, 0, 0, 0, 0, 0,
+    "1 month 15 days 12 hours should be exactly 1.5 months, which rounds up to 2 months");
+  TemporalHelpers.assertDuration(duration.round({ smallestUnit: "months", roundingMode: 'halfTrunc', relativeTo }),
+    0, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+    "1 month 15 days 12 hours should be exactly 1.5 months, which rounds down to 1 month");
+}
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const duration = new Temporal.Duration(0, 1, 0, 15);
+  const relativeTo = new Temporal.ZonedDateTime(
+    951991200_000_000_000n /* = 2000-03-02T10Z */,
+    timeZone); /* = 2000-03-02T02-08 in local time */
+
+  TemporalHelpers.assertDuration(duration.round({ smallestUnit: "months", relativeTo }),
+    0, 2, 0, 0, 0, 0, 0, 0, 0, 0,
+    "1 month 15 days should be exactly 1.5 months, which rounds up to 2 months");
+  TemporalHelpers.assertDuration(duration.round({ smallestUnit: "months", roundingMode: 'halfTrunc', relativeTo }),
+    0, 1, 0, 0, 0, 0, 0, 0, 0, 0,
+    "1 month 15 days should be exactly 1.5 months, which rounds down to 1 month");
+}
diff --git a/test/built-ins/Temporal/Duration/prototype/total/dst-rounding-result.js b/test/built-ins/Temporal/Duration/prototype/total/dst-rounding-result.js
@@ -0,0 +1,37 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-temporal.duration.prototype.total
+description: >
+    Rounding the resulting duration takes the time zone's UTC offset shifts
+    into account
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+// Based on a test case by Adam Shaw
+
+{
+  // Date part of duration lands on skipped DST hour, causing disambiguation
+  const duration = new Temporal.Duration(0, 1, 0, 15, 12);
+  const relativeTo = new Temporal.ZonedDateTime(
+    950868000_000_000_000n /* = 2000-02-18T10Z */,
+    timeZone); /* = 2000-02-18T02-08 in local time */
+
+  assert.sameValue(duration.total({ unit: "months", relativeTo }), 1.5,
+    "1 month 15 days 12 hours should be exactly 1.5 months");
+}
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const duration = new Temporal.Duration(0, 1, 0, 15);
+  const relativeTo = new Temporal.ZonedDateTime(
+    951991200_000_000_000n /* = 2000-03-02T10Z */,
+    timeZone); /* = 2000-03-02T02-08 in local time */
+
+  assert.sameValue(duration.total({ unit: "months", relativeTo }), 1.5,
+    "1 month 15 days should be exactly 1.5 months");
+}
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/since/dst-rounding-result.js b/test/built-ins/Temporal/ZonedDateTime/prototype/since/dst-rounding-result.js
@@ -0,0 +1,45 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-temporal.zoneddatetime.prototype.since
+description: >
+    Rounding the resulting duration takes the time zone's UTC offset shifts
+    into account
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Based on a test case by Adam Shaw
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const start = new Temporal.ZonedDateTime(
+    950868000_000_000_000n /* = 2000-02-18T10Z */,
+    timeZone); /* = 2000-02-18T02-08 in local time */
+  const end = new Temporal.ZonedDateTime(
+    954709200_000_000_000n /* = 2000-04-02T21Z */,
+    timeZone); /* = 2000-04-02T14-07 in local time */
+
+  const duration = start.since(end, { largestUnit: "months" });
+  TemporalHelpers.assertDuration(duration, 0, -1, 0, -15, -11, 0, 0, 0, 0, 0,
+    "1-month rounding window is shortened by DST");
+}
+
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const start = new Temporal.ZonedDateTime(
+    951991200_000_000_000n /* = 2000-03-02T10Z */,
+    timeZone); /* = 2000-03-02T02-08 in local time */
+  const end = new Temporal.ZonedDateTime(
+    956005200_000_000_000n /* = 2000-04-17T21Z */,
+    timeZone); /* = 2000-04-17T14-07 in local time */
+
+  const duration = start.since(end, { largestUnit: "months" });
+  TemporalHelpers.assertDuration(duration, 0, -1, 0, -15, -12, 0, 0, 0, 0, 0,
+    "1-month rounding window is not shortened by DST");
+}
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/dst-rounding-result.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/dst-rounding-result.js
@@ -0,0 +1,45 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-temporal.zoneddatetime.prototype.until
+description: >
+    Rounding the resulting duration takes the time zone's UTC offset shifts
+    into account
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Based on a test case by Adam Shaw
+
+const timeZone = TemporalHelpers.springForwardFallBackTimeZone();
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const start = new Temporal.ZonedDateTime(
+    950868000_000_000_000n /* = 2000-02-18T10Z */,
+    timeZone); /* = 2000-02-18T02-08 in local time */
+  const end = new Temporal.ZonedDateTime(
+    954709200_000_000_000n /* = 2000-04-02T21Z */,
+    timeZone); /* = 2000-04-02T14-07 in local time */
+
+  const duration = start.until(end, { largestUnit: "months" });
+  TemporalHelpers.assertDuration(duration, 0, 1, 0, 15, 11, 0, 0, 0, 0, 0,
+    "1-month rounding window is shortened by DST");
+}
+
+
+{
+  // Month-only part of duration lands on skipped DST hour, should not cause
+  // disambiguation
+  const start = new Temporal.ZonedDateTime(
+    951991200_000_000_000n /* = 2000-03-02T10Z */,
+    timeZone); /* = 2000-03-02T02-08 in local time */
+  const end = new Temporal.ZonedDateTime(
+    956005200_000_000_000n /* = 2000-04-17T21Z */,
+    timeZone); /* = 2000-04-17T14-07 in local time */
+
+  const duration = start.until(end, { largestUnit: "months" });
+  TemporalHelpers.assertDuration(duration, 0, 1, 0, 15, 12, 0, 0, 0, 0, 0,
+    "1-month rounding window is not shortened by DST");
+}