From 70e71db8c8135bc832520b1435c9a6bc7977436e Mon Sep 17 00:00:00 2001
From: Philip Chimento <pchimento@igalia.com>
Date: Tue, 2 May 2023 11:12:51 -0700
Subject: [PATCH 1/2] Tests for Duration rounding bug when rounding crosses a
 unit boundary

See https://github.com/tc39/proposal-temporal/issues/2563

The old behaviour was encoded in one test in staging, but the behaviour of
largestUnit in duration rounding has changed since that test was written.
Therefore I'm assuming that toString() should've been updated when that
happened.
---
 .../round/round-cross-unit-boundary.js        | 47 +++++++++++++++++++
 .../toString/round-cross-unit-boundary.js     | 40 ++++++++++++++++
 .../since/round-cross-unit-boundary.js        | 14 ++++++
 .../until/round-cross-unit-boundary.js        | 14 ++++++
 .../since/round-cross-unit-boundary.js        | 14 ++++++
 .../until/round-cross-unit-boundary.js        | 14 ++++++
 .../since/round-cross-unit-boundary.js        | 33 +++++++++++++
 .../until/round-cross-unit-boundary.js        | 33 +++++++++++++
 .../since/round-cross-unit-boundary.js        | 14 ++++++
 .../until/round-cross-unit-boundary.js        | 14 ++++++
 .../since/round-cross-unit-boundary.js        | 14 ++++++
 .../until/round-cross-unit-boundary.js        | 14 ++++++
 .../since/round-cross-unit-boundary.js        | 33 +++++++++++++
 .../until/round-cross-unit-boundary.js        | 33 +++++++++++++
 .../staging/Temporal/Duration/old/toString.js |  7 ---
 15 files changed, 331 insertions(+), 7 deletions(-)
 create mode 100644 test/built-ins/Temporal/Duration/prototype/round/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/Duration/prototype/toString/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/Instant/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/Instant/prototype/until/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainDate/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainDate/prototype/until/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainDateTime/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainDateTime/prototype/until/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainTime/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainTime/prototype/until/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainYearMonth/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/PlainYearMonth/prototype/until/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/ZonedDateTime/prototype/since/round-cross-unit-boundary.js
 create mode 100644 test/built-ins/Temporal/ZonedDateTime/prototype/until/round-cross-unit-boundary.js

diff --git a/test/built-ins/Temporal/Duration/prototype/round/round-cross-unit-boundary.js b/test/built-ins/Temporal/Duration/prototype/round/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..51870b56c3a
--- /dev/null
+++ b/test/built-ins/Temporal/Duration/prototype/round/round-cross-unit-boundary.js
@@ -0,0 +1,47 @@
+// Copyright (C) 2023 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 can cross unit boundaries up to the implicit largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const relativeTo = new Temporal.PlainDate(2022, 1, 1);
+const roundingMode = "expand";
+
+// Positive, date units
+{
+  const duration = new Temporal.Duration(1, 11, 0, 24);
+  const result = duration.round({ smallestUnit: "months", roundingMode, relativeTo });
+  TemporalHelpers.assertDuration(result, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "1 year 12 months balances to 2 years");
+}
+
+// Negative, date units
+{
+  const duration = new Temporal.Duration(-1, -11, 0, -24);
+  const result = duration.round({ smallestUnit: "months", roundingMode, relativeTo });
+  TemporalHelpers.assertDuration(result, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "-1 year -12 months balances to -2 years");
+}
+
+// Positive, time units
+{
+  const duration = new Temporal.Duration(0, 0, 0, 0, 1, 59, 59, 900);
+  const result = duration.round({ smallestUnit: "seconds", roundingMode });
+  TemporalHelpers.assertDuration(result, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, "1:59:60 balances to 2 hours");
+}
+
+// Negative, time units
+{
+  const duration = new Temporal.Duration(0, 0, 0, 0, -1, -59, -59, -900);
+  const result = duration.round({ smallestUnit: "seconds", roundingMode });
+  TemporalHelpers.assertDuration(result, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, "-1:59:60 balances to -2 hours");
+}
+
+// No balancing if smallest unit is largest unit
+{
+  const duration = new Temporal.Duration(0, 11, 0, 24);
+  const result = duration.round({ smallestUnit: "months", roundingMode, relativeTo });
+  TemporalHelpers.assertDuration(result, 0, 12, 0, 0, 0, 0, 0, 0, 0, 0, "12 months stays as is");
+}
diff --git a/test/built-ins/Temporal/Duration/prototype/toString/round-cross-unit-boundary.js b/test/built-ins/Temporal/Duration/prototype/toString/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..e46999f3bee
--- /dev/null
+++ b/test/built-ins/Temporal/Duration/prototype/toString/round-cross-unit-boundary.js
@@ -0,0 +1,40 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.duration.prototype.tostring
+description: Rounding can cross unit boundaries up to days
+features: [Temporal]
+---*/
+
+const roundingMode = "expand";
+
+// Positive, time units
+{
+  const duration = new Temporal.Duration(0, 0, 0, 0, 1, 59, 59, 900);
+  assert.sameValue(duration.toString({ fractionalSecondDigits: 0, roundingMode }), "PT2H0S", "1:59:60 balances to 2 hours");
+}
+
+// Negative, time units
+{
+  const duration = new Temporal.Duration(0, 0, 0, 0, -1, -59, -59, -900);
+  assert.sameValue(duration.toString({ fractionalSecondDigits: 0, roundingMode }), "-PT2H0S", "-1:59:60 balances to -2 hours");
+}
+
+// Positive, date and time units
+{
+  const duration = new Temporal.Duration(1, 11, 0, 30, 23, 59, 59, 999, 999, 999);
+  assert.sameValue(duration.toString({ fractionalSecondDigits: 8, roundingMode }), "P1Y11M31DT0.00000000S", "units balance only up to days (positive)");
+}
+
+// Negative, date and time units
+{
+  const duration = new Temporal.Duration(-1, -11, 0, -30, -23, -59, -59, -999, -999, -999);
+  assert.sameValue(duration.toString({ fractionalSecondDigits: 8, roundingMode }), "-P1Y11M31DT0.00000000S", "units balance only up to days (negative)");
+}
+
+// No balancing if smallest unit is largest unit
+{
+  const duration = new Temporal.Duration(0, 0, 0, 0, 0, 0, 59, 900);
+  assert.sameValue(duration.toString({ fractionalSecondDigits: 0, roundingMode }), "PT60S", "60 seconds stays as is");
+}
diff --git a/test/built-ins/Temporal/Instant/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/Instant/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..eec78d95881
--- /dev/null
+++ b/test/built-ins/Temporal/Instant/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.instant.prototype.since
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.Instant(0n);
+const later = new Temporal.Instant(7199_000_000_000n);
+const duration = earlier.since(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, "-1:59 balances to -2 hours");
diff --git a/test/built-ins/Temporal/Instant/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/Instant/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..1fbf2148dde
--- /dev/null
+++ b/test/built-ins/Temporal/Instant/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.instant.prototype.until
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.Instant(0n);
+const later = new Temporal.Instant(7199_000_000_000n);
+const duration = earlier.until(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, "1:59 balances to 2 hours");
diff --git a/test/built-ins/Temporal/PlainDate/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainDate/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..34db4ccac3e
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDate/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.since
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainDate(2022, 1, 1);
+const later = new Temporal.PlainDate(2023, 12, 25);
+const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "-1 year -11 months balances to -2 years");
diff --git a/test/built-ins/Temporal/PlainDate/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainDate/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..136ae36a04d
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDate/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.until
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainDate(2022, 1, 1);
+const later = new Temporal.PlainDate(2023, 12, 25);
+const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "1 year 11 months balances to 2 years");
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainDateTime/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..59a453eaba5
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.prototype.since
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Date units
+{
+  const earlier = new Temporal.PlainDateTime(2022, 1, 1);
+  const later = new Temporal.PlainDateTime(2023, 12, 25);
+  const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "-1 year -11 months balances to -2 years");
+}
+
+// Time units
+{
+  const earlier = new Temporal.PlainDateTime(2000, 5, 2);
+  const later = new Temporal.PlainDateTime(2000, 5, 2, 1, 59, 59);
+  const duration = earlier.since(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, "-1:59 balances to -2 hours");
+}
+
+// Both
+{
+  const earlier = new Temporal.PlainDateTime(1970, 1, 1);
+  const later = new Temporal.PlainDateTime(1971, 12, 31, 23, 59, 59, 999, 999, 999);
+  const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "microseconds", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "rounding down 1 ns balances to -2 years");
+}
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainDateTime/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..24cfb6ce582
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.prototype.until
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Date units
+{
+  const earlier = new Temporal.PlainDateTime(2022, 1, 1);
+  const later = new Temporal.PlainDateTime(2023, 12, 25);
+  const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "1 year 11 months balances to 2 years");
+}
+
+// Time units
+{
+  const earlier = new Temporal.PlainDateTime(2000, 5, 2);
+  const later = new Temporal.PlainDateTime(2000, 5, 2, 1, 59, 59);
+  const duration = earlier.until(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, "1:59 balances to 2 hours");
+}
+
+// Both
+{
+  const earlier = new Temporal.PlainDateTime(1970, 1, 1);
+  const later = new Temporal.PlainDateTime(1971, 12, 31, 23, 59, 59, 999, 999, 999);
+  const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "microseconds", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "rounding up 1 ns balances to 2 years");
+}
diff --git a/test/built-ins/Temporal/PlainTime/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainTime/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..8d018740a26
--- /dev/null
+++ b/test/built-ins/Temporal/PlainTime/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.since
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime();
+const later = new Temporal.PlainTime(1, 59, 59);
+const duration = earlier.since(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, "-1:60 balances to -2 hours");
diff --git a/test/built-ins/Temporal/PlainTime/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainTime/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..7f5e0a95e74
--- /dev/null
+++ b/test/built-ins/Temporal/PlainTime/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaintime.prototype.until
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainTime();
+const later = new Temporal.PlainTime(1, 59, 59);
+const duration = earlier.until(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, "1:60 balances to 2 hours");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainYearMonth/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..06c782ff0d1
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.prototype.since
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainYearMonth(2022, 1);
+const later = new Temporal.PlainYearMonth(2023, 12);
+const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "months", roundingIncrement: 3, roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "-1 year -12 months balances to -2 years");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/PlainYearMonth/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..54cb3ac26f9
--- /dev/null
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2023 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plainyearmonth.prototype.until
+description: Rounding can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const earlier = new Temporal.PlainYearMonth(2022, 1);
+const later = new Temporal.PlainYearMonth(2023, 12);
+const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "months", roundingIncrement: 3, roundingMode: "expand" });
+TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "1 year 12 months balances to 2 years");
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/since/round-cross-unit-boundary.js b/test/built-ins/Temporal/ZonedDateTime/prototype/since/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..5063f7afee7
--- /dev/null
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/since/round-cross-unit-boundary.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2023 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 can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Date units
+{
+  const earlier = new Temporal.ZonedDateTime(1640995200_000_000_000n /* = 2022-01-01T00 */, "UTC");
+  const later = new Temporal.ZonedDateTime(1703462400_000_000_000n /* = 2023-12-25T00 */, "UTC");
+  const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "-1 year -11 months balances to -2 years");
+}
+
+// Time units
+{
+  const earlier = new Temporal.ZonedDateTime(0n, "UTC");
+  const later = new Temporal.ZonedDateTime(7199_000_000_000n, "UTC");
+  const duration = earlier.since(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, -2, 0, 0, 0, 0, 0, "-1:59 balances to -2 hours");
+}
+
+// Both
+{
+  const earlier = new Temporal.ZonedDateTime(0n, "UTC");
+  const later = new Temporal.ZonedDateTime(63071999_999_999_999n /* = 1971-12-31T23:59:59.999999999 */, "UTC");
+  const duration = earlier.since(later, { largestUnit: "years", smallestUnit: "microseconds", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, -2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "rounding down 1 ns balances to -2 years");
+}
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/round-cross-unit-boundary.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/round-cross-unit-boundary.js
new file mode 100644
index 00000000000..e6c3f1a3605
--- /dev/null
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/until/round-cross-unit-boundary.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2023 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 can cross unit boundaries up to largestUnit
+includes: [temporalHelpers.js]
+features: [Temporal]
+---*/
+
+// Date units
+{
+  const earlier = new Temporal.ZonedDateTime(1640995200_000_000_000n /* = 2022-01-01T00 */, "UTC");
+  const later = new Temporal.ZonedDateTime(1703462400_000_000_000n /* = 2023-12-25T00 */, "UTC");
+  const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "months", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "1 year 11 months balances to 2 years");
+}
+
+// Time units
+{
+  const earlier = new Temporal.ZonedDateTime(0n, "UTC");
+  const later = new Temporal.ZonedDateTime(7199_000_000_000n, "UTC");
+  const duration = earlier.until(later, { largestUnit: "hours", smallestUnit: "minutes", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, "1:59 balances to 2 hours");
+}
+
+// Both
+{
+  const earlier = new Temporal.ZonedDateTime(0n, "UTC");
+  const later = new Temporal.ZonedDateTime(63071999_999_999_999n /* = 1971-12-31T23:59:59.999999999 */, "UTC");
+  const duration = earlier.until(later, { largestUnit: "years", smallestUnit: "microseconds", roundingMode: "expand" });
+  TemporalHelpers.assertDuration(duration, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, "rounding up 1 ns balances to 2 years");
+}
diff --git a/test/staging/Temporal/Duration/old/toString.js b/test/staging/Temporal/Duration/old/toString.js
index a08ddf020ce..99fc1e08db3 100644
--- a/test/staging/Temporal/Duration/old/toString.js
+++ b/test/staging/Temporal/Duration/old/toString.js
@@ -23,10 +23,3 @@ var d = Temporal.Duration.from({
   microseconds: Number.MAX_SAFE_INTEGER
 });
 assert.sameValue(`${ d }`, "PT9016206453995.731991S");
-
-// rounding can affect units up to seconds
-var d4 = Temporal.Duration.from("P1Y1M1W1DT23H59M59.999999999S");
-assert.sameValue(d4.toString({
-  fractionalSecondDigits: 8,
-  roundingMode: "halfExpand"
-}), "P1Y1M1W1DT23H59M60.00000000S");

From 0523ef7cc016b66f939fe9442d8a5e773ec752ce Mon Sep 17 00:00:00 2001
From: Philip Chimento <pchimento@igalia.com>
Date: Wed, 3 May 2023 12:21:56 -0700
Subject: [PATCH 2/2] Adjustments to tests for added invocations of
 BalanceDurationRelative

In order to fix tc39/proposal-temporal#2563, we added invocations of
BalanceDurationRelative after some invocations of RoundDuration. These
cause observable calendar calls, which must be accounted for in some
existing tests.
---
 .../prototype/since/order-of-operations.js    | 26 ++++++++++++++---
 .../prototype/until/order-of-operations.js    | 26 ++++++++++++++---
 .../prototype/since/order-of-operations.js    | 26 ++++++++++++++---
 .../prototype/until/order-of-operations.js    | 26 ++++++++++++++---
 .../prototype/since/order-of-operations.js    | 28 ++++++++++++++++---
 .../since/roundingincrement-non-integer.js    |  2 +-
 .../prototype/until/order-of-operations.js    | 28 ++++++++++++++++---
 .../until/roundingincrement-non-integer.js    |  2 +-
 ...r-dateadd-called-with-options-undefined.js |  3 +-
 ...euntil-called-with-singular-largestunit.js |  4 +--
 .../prototype/since/order-of-operations.js    | 21 ++++++++++++--
 ...r-dateadd-called-with-options-undefined.js |  3 +-
 ...euntil-called-with-singular-largestunit.js |  4 +--
 .../prototype/until/order-of-operations.js    | 21 ++++++++++++--
 14 files changed, 182 insertions(+), 38 deletions(-)

diff --git a/test/built-ins/Temporal/PlainDate/prototype/since/order-of-operations.js b/test/built-ins/Temporal/PlainDate/prototype/since/order-of-operations.js
index df0b0d03122..aa45194b3ac 100644
--- a/test/built-ins/Temporal/PlainDate/prototype/since/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainDate/prototype/since/order-of-operations.js
@@ -136,7 +136,13 @@ const expectedOpsForYearRounding = expected.concat([
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -159,7 +165,13 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherDatePropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months/weeks");
 actual.splice(0); // clear
@@ -175,7 +187,10 @@ const expectedOpsForMonthRounding = expected.concat([
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.since(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
@@ -189,6 +204,9 @@ const expectedOpsForWeekRounding = expected.concat([
   "call this.calendar.dateUntil",
   // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.since(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
diff --git a/test/built-ins/Temporal/PlainDate/prototype/until/order-of-operations.js b/test/built-ins/Temporal/PlainDate/prototype/until/order-of-operations.js
index b61c7465f5f..373072e6260 100644
--- a/test/built-ins/Temporal/PlainDate/prototype/until/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainDate/prototype/until/order-of-operations.js
@@ -137,7 +137,13 @@ const expectedOpsForYearRounding = expected.concat([
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -160,7 +166,13 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDatePropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months/weeks");
 actual.splice(0); // clear
@@ -176,7 +188,10 @@ const expectedOpsForMonthRounding = expected.concat([
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.until(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
@@ -190,6 +205,9 @@ const expectedOpsForWeekRounding = expected.concat([
   "call this.calendar.dateUntil",
   // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.until(otherDatePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/since/order-of-operations.js b/test/built-ins/Temporal/PlainDateTime/prototype/since/order-of-operations.js
index ca4cde85b13..048024860f9 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/since/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/since/order-of-operations.js
@@ -166,7 +166,13 @@ const expectedOpsForYearRounding = expected.concat([
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -195,7 +201,13 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDatePropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months/weeks");
 actual.splice(0); // clear
@@ -211,7 +223,10 @@ const expectedOpsForMonthRounding = expected.concat([
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
@@ -225,6 +240,9 @@ const expectedOpsForWeekRounding = expected.concat([
   "call this.calendar.dateUntil",
   // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/until/order-of-operations.js b/test/built-ins/Temporal/PlainDateTime/prototype/until/order-of-operations.js
index e937fdbdb6e..026a443b57c 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/until/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/until/order-of-operations.js
@@ -166,7 +166,13 @@ const expectedOpsForYearRounding = expected.concat([
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -195,7 +201,13 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDatePropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months/weeks");
 actual.splice(0); // clear
@@ -211,7 +223,10 @@ const expectedOpsForMonthRounding = expected.concat([
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -225,6 +240,9 @@ const expectedOpsForWeekRounding = expected.concat([
   "call this.calendar.dateUntil",
   // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/since/order-of-operations.js b/test/built-ins/Temporal/PlainYearMonth/prototype/since/order-of-operations.js
index 55e4b575071..5757cce9f5f 100644
--- a/test/built-ins/Temporal/PlainYearMonth/prototype/since/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/since/order-of-operations.js
@@ -161,11 +161,18 @@ actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest year:
 const expectedOpsForYearRounding = expected.concat([
+  // RoundDuration
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherYearMonthPropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -181,16 +188,29 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherYearMonthPropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
-assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years");
+assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest month:
 const expectedOpsForMonthRounding = expected.concat([
+  // RoundDuration
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherYearMonthPropertyBag, createOptionsObserver({ smallestUnit: "months", roundingIncrement: 2 }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/since/roundingincrement-non-integer.js b/test/built-ins/Temporal/PlainYearMonth/prototype/since/roundingincrement-non-integer.js
index 985ee9f20be..97513e21477 100644
--- a/test/built-ins/Temporal/PlainYearMonth/prototype/since/roundingincrement-non-integer.js
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/since/roundingincrement-non-integer.js
@@ -20,5 +20,5 @@ const earlier = new Temporal.PlainYearMonth(2000, 5);
 const later = new Temporal.PlainYearMonth(2000, 10);
 const result = later.since(earlier, { roundingIncrement: 2.5, roundingMode: "trunc" });
 TemporalHelpers.assertDuration(result, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, "roundingIncrement 2.5 truncates to 2");
-const result2 = later.since(earlier, { smallestUnit: "months", roundingIncrement: 1e9 + 0.5, roundingMode: "expand" });
+const result2 = later.since(earlier, { largestUnit: "months", smallestUnit: "months", roundingIncrement: 1e9 + 0.5, roundingMode: "expand" });
 TemporalHelpers.assertDuration(result2, 0, 1e9, 0, 0, 0, 0, 0, 0, 0, 0, "roundingIncrement 1e9 + 0.5 truncates to 1e9");
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/until/order-of-operations.js b/test/built-ins/Temporal/PlainYearMonth/prototype/until/order-of-operations.js
index cbeb40b2975..11c3d93769d 100644
--- a/test/built-ins/Temporal/PlainYearMonth/prototype/until/order-of-operations.js
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/until/order-of-operations.js
@@ -161,11 +161,18 @@ actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest year:
 const expectedOpsForYearRounding = expected.concat([
+  // RoundDuration
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherYearMonthPropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
@@ -181,17 +188,30 @@ const expectedOpsForYearRoundingSameMonth = expected.concat([
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.o not called because months and weeks == 0)
+  // (7.o not called because months and weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherYearMonthPropertyBagSameMonth, createOptionsObserver({ smallestUnit: "years" }));
-assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years");
+assert.compareArray(actual, expectedOpsForYearRoundingSameMonth, "order of operations with smallestUnit = years and no excess months");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest month:
 const expectedOpsForMonthRounding = expected.concat([
+  // RoundDuration
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherYearMonthPropertyBag, createOptionsObserver({ smallestUnit: "months", roundingIncrement: 2 }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
diff --git a/test/built-ins/Temporal/PlainYearMonth/prototype/until/roundingincrement-non-integer.js b/test/built-ins/Temporal/PlainYearMonth/prototype/until/roundingincrement-non-integer.js
index 0f7f40bec57..84360e132c2 100644
--- a/test/built-ins/Temporal/PlainYearMonth/prototype/until/roundingincrement-non-integer.js
+++ b/test/built-ins/Temporal/PlainYearMonth/prototype/until/roundingincrement-non-integer.js
@@ -20,5 +20,5 @@ const earlier = new Temporal.PlainYearMonth(2000, 5);
 const later = new Temporal.PlainYearMonth(2000, 10);
 const result = earlier.until(later, { roundingIncrement: 2.5, roundingMode: "trunc" });
 TemporalHelpers.assertDuration(result, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, "roundingIncrement 2.5 truncates to 2");
-const result2 = earlier.until(later, { smallestUnit: "months", roundingIncrement: 1e9 + 0.5, roundingMode: "expand" });
+const result2 = earlier.until(later, { largestUnit: "months", smallestUnit: "months", roundingIncrement: 1e9 + 0.5, roundingMode: "expand" });
 TemporalHelpers.assertDuration(result2, 0, 1e9, 0, 0, 0, 0, 0, 0, 0, 0, "roundingIncrement 1e9 + 0.5 truncates to 1e9");
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateadd-called-with-options-undefined.js b/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateadd-called-with-options-undefined.js
index ea8e220b1e8..72048fde25e 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateadd-called-with-options-undefined.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateadd-called-with-options-undefined.js
@@ -29,8 +29,9 @@ assert.sameValue(calendar.dateAddCallCount, 1, "basic difference with largestUni
 //   RoundDuration ->
 //     MoveRelativeZonedDateTime -> AddZonedDateTime -> calendar.dateAdd()
 //     MoveRelativeDate -> calendar.dateAdd()
+//   BalanceDurationRelative -> MoveRelativeDate -> calendar.dateAdd()
 
 calendar.dateAddCallCount = 0;
 
 later1.since(earlier, { smallestUnit: "weeks" });
-assert.sameValue(calendar.dateAddCallCount, 3, "rounding difference with calendar smallestUnit");
+assert.sameValue(calendar.dateAddCallCount, 4, "rounding difference with calendar smallestUnit");
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateuntil-called-with-singular-largestunit.js b/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateuntil-called-with-singular-largestunit.js
index 6f6e4eaf085..3a6248bb210 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateuntil-called-with-singular-largestunit.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/since/calendar-dateuntil-called-with-singular-largestunit.js
@@ -77,7 +77,7 @@ TemporalHelpers.checkCalendarDateUntilLargestUnitSingular(
     later.since(earlier, { largestUnit, roundingIncrement: 2, roundingMode: 'ceil' });
   },
   {
-    years: ["year", "year"],
+    years: ["year", "year", "month"],
     months: ["month", "month"],
     weeks: ["week", "week"],
     days: [],
@@ -100,7 +100,7 @@ TemporalHelpers.checkCalendarDateUntilLargestUnitSingular(
     later.since(earlier, { smallestUnit });
   },
   {
-    years: ["year", "year"],
+    years: ["year", "year", "month"],
     months: ["month"],
     weeks: ["week"],
     days: [],
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/since/order-of-operations.js b/test/built-ins/Temporal/ZonedDateTime/prototype/since/order-of-operations.js
index f232acb18d1..f52574cae72 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/since/order-of-operations.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/since/order-of-operations.js
@@ -358,29 +358,44 @@ actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest year:
 const expectedOpsForYearRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest month:
 const expectedOpsForMonthRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest week:
 const expectedOpsForWeekRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.since(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
 actual.splice(0); // clear
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateadd-called-with-options-undefined.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateadd-called-with-options-undefined.js
index 82cdb9e137f..f09efe1221b 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateadd-called-with-options-undefined.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateadd-called-with-options-undefined.js
@@ -29,8 +29,9 @@ assert.sameValue(calendar.dateAddCallCount, 1, "basic difference with largestUni
 //   RoundDuration ->
 //     MoveRelativeZonedDateTime -> AddZonedDateTime -> calendar.dateAdd()
 //     MoveRelativeDate -> calendar.dateAdd()
+//   BalanceDurationRelative -> MoveRelativeDate -> calendar.dateAdd()
 
 calendar.dateAddCallCount = 0;
 
 earlier.until(later1, { smallestUnit: "weeks" });
-assert.sameValue(calendar.dateAddCallCount, 3, "rounding difference with calendar smallestUnit");
+assert.sameValue(calendar.dateAddCallCount, 4, "rounding difference with calendar smallestUnit");
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateuntil-called-with-singular-largestunit.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateuntil-called-with-singular-largestunit.js
index 6842f08dcf8..045de138560 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateuntil-called-with-singular-largestunit.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/until/calendar-dateuntil-called-with-singular-largestunit.js
@@ -77,7 +77,7 @@ TemporalHelpers.checkCalendarDateUntilLargestUnitSingular(
     earlier.until(later, { largestUnit, roundingIncrement: 2, roundingMode: 'ceil' });
   },
   {
-    years: ["year", "year"],
+    years: ["year", "year", "month"],
     months: ["month", "month"],
     weeks: ["week", "week"],
     days: [],
@@ -100,7 +100,7 @@ TemporalHelpers.checkCalendarDateUntilLargestUnitSingular(
     earlier.until(later, { smallestUnit });
   },
   {
-    years: ["year", "year"],
+    years: ["year", "year", "month"],
     months: ["month"],
     weeks: ["week"],
     days: [],
diff --git a/test/built-ins/Temporal/ZonedDateTime/prototype/until/order-of-operations.js b/test/built-ins/Temporal/ZonedDateTime/prototype/until/order-of-operations.js
index d15ccfe5a2a..893444ccec2 100644
--- a/test/built-ins/Temporal/ZonedDateTime/prototype/until/order-of-operations.js
+++ b/test/built-ins/Temporal/ZonedDateTime/prototype/until/order-of-operations.js
@@ -358,29 +358,44 @@ actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest year:
 const expectedOpsForYearRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",    // 7.e
   "call this.calendar.dateAdd",    // 7.g
   "call this.calendar.dateUntil",  // 7.o
   "call this.calendar.dateAdd",    // 7.y MoveRelativeDate
-]);  // (7.s not called because other units can't add up to >1 year at this point)
+  // (7.s not called because other units can't add up to >1 year at this point)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 11.c MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.g MoveRelativeDate
+  "call this.calendar.dateAdd",    // 11.k
+  "call this.calendar.dateUntil"   // 11.n
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "years" }));
 assert.compareArray(actual, expectedOpsForYearRounding, "order of operations with smallestUnit = years");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest month:
 const expectedOpsForMonthRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",    // 10.c
   "call this.calendar.dateAdd",    // 10.e
   "call this.calendar.dateAdd",    // 10.k MoveRelativeDate
-]);  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // (10.n.iii MoveRelativeDate not called because weeks == 0)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 12.b MoveRelativeDate
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "months" }));
 assert.compareArray(actual, expectedOpsForMonthRounding, "order of operations with smallestUnit = months");
 actual.splice(0); // clear
 
 // code path through RoundDuration that rounds to the nearest week:
 const expectedOpsForWeekRounding = expected.concat(expectedOpsForCalendarDifference, expectedOpsForCalendarRounding, [
+  // RoundDuration
   "call this.calendar.dateAdd",  // 11.d MoveRelativeDate
-]);  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // (11.g.iii MoveRelativeDate not called because days already balanced)
+  // BalanceDurationRelative
+  "call this.calendar.dateAdd",    // 13.c MoveRelativeDate
+]);
 instance.until(otherDateTimePropertyBag, createOptionsObserver({ smallestUnit: "weeks" }));
 assert.compareArray(actual, expectedOpsForWeekRounding, "order of operations with smallestUnit = weeks");
 actual.splice(0);  // clear