diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date-time.js b/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date-time.js
new file mode 100644
index 0000000000..8d99c84bb5
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date-time.js
@@ -0,0 +1,35 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinmonth
+description: Temporal.Calendar.prototype.daysInMonth will take Temporal.PlainDateTime object
+  and return the number of days in that month.
+  and return Array of the same content.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slots, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInMonth(temporalDateLike.[[ISOYear]], temporalDateLike.[[ISOMonth]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 1, 23, 5, 30, 13)));
+// leap year
+assert.sameValue(29, cal.daysInMonth(new Temporal.PlainDateTime(1996, 2, 23, 5, 30, 13)));
+assert.sameValue(29, cal.daysInMonth(new Temporal.PlainDateTime(2000, 2, 23, 5, 30, 13)));
+// non leap year
+assert.sameValue(28, cal.daysInMonth(new Temporal.PlainDateTime(1997, 2, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 3, 23, 5, 30, 13)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDateTime(1997, 4, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 5, 23, 5, 30, 13)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDateTime(1997, 6, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 7, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 8, 23, 5, 30, 13)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDateTime(1997, 9, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 10, 23, 5, 30, 13)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDateTime(1997, 11, 23, 5, 30, 13)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDateTime(1997, 12, 23, 5, 30, 13)));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date.js b/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date.js
new file mode 100644
index 0000000000..5453a298fd
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-month/plain-date.js
@@ -0,0 +1,35 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinmonth
+description: Temporal.Calendar.prototype.daysInMonth will take Temporal.PlainDate object
+  and return the number of days in that month.
+  and return Array of the same content.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slots, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInMonth(temporalDateLike.[[ISOYear]], temporalDateLike.[[ISOMonth]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 1, 15)));
+// leap year
+assert.sameValue(29, cal.daysInMonth(new Temporal.PlainDate(2020, 2, 15)));
+assert.sameValue(29, cal.daysInMonth(new Temporal.PlainDate(2000, 2, 15)));
+// non-leap year
+assert.sameValue(28, cal.daysInMonth(new Temporal.PlainDate(2021, 2, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 3, 15)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDate(2021, 4, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 5, 15)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDate(2021, 6, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 7, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 8, 15)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDate(2021, 9, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 10, 15)));
+assert.sameValue(30, cal.daysInMonth(new Temporal.PlainDate(2021, 11, 15)));
+assert.sameValue(31, cal.daysInMonth(new Temporal.PlainDate(2021, 12, 15)));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-month/string.js b/test/built-ins/Temporal/Calendar/prototype/days-in-month/string.js
new file mode 100644
index 0000000000..a4eb883b5e
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-month/string.js
@@ -0,0 +1,34 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinmonth
+description: Temporal.Calendar.prototype.daysInMonth will take ISO8601 string
+  and return the number of days in that month.
+  and return Array of the same content.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slots, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInMonth(temporalDateLike.[[ISOYear]], temporalDateLike.[[ISOMonth]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(31, cal.daysInMonth("2019-01-18"));
+// leap year
+assert.sameValue(29, cal.daysInMonth("2020-02-18"));
+// non leap
+assert.sameValue(28, cal.daysInMonth("2019-02-18"));
+assert.sameValue(31, cal.daysInMonth("2019-03-18"));
+assert.sameValue(30, cal.daysInMonth("2019-04-18"));
+assert.sameValue(31, cal.daysInMonth("2019-05-18"));
+assert.sameValue(30, cal.daysInMonth("2019-06-18"));
+assert.sameValue(31, cal.daysInMonth("2019-07-18"));
+assert.sameValue(31, cal.daysInMonth("2019-08-18"));
+assert.sameValue(30, cal.daysInMonth("2019-09-18"));
+assert.sameValue(31, cal.daysInMonth("2019-10-18"));
+assert.sameValue(30, cal.daysInMonth("2019-11-18"));
+assert.sameValue(31, cal.daysInMonth("2019-12-18"));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-week/simple.js b/test/built-ins/Temporal/Calendar/prototype/days-in-week/simple.js
new file mode 100644
index 0000000000..2673067598
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-week/simple.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinweeks
+description: Temporal.Calendar.prototype.daysInWeek will take different kind of object
+  and return 7.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. Perform ? ToTemporalDate(temporalDateLike).
+  5. Return 7𝔽.
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(7, cal.daysInWeek(new Temporal.PlainDate(2021, 7, 15)));
+assert.sameValue(7, cal.daysInWeek(new Temporal.PlainDateTime(1997, 8, 23, 5, 30, 13)));
+assert.sameValue(7, cal.daysInWeek("2019-03-18"));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date-time.js b/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date-time.js
new file mode 100644
index 0000000000..8eed6719a3
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date-time.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinyear
+description: Temporal.Calendar.prototype.daysInYear will take PlainDateTime and return
+  the number of days in a year.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slot, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInYear(temporalDateLike.[[ISOYear]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1995, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(1996, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1997, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1998, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1999, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(2000, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2001, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2002, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2003, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(2004, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2005, 8, 23, 5, 30, 13)));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date.js b/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date.js
new file mode 100644
index 0000000000..f3b4905819
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-year/plain-date.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinyear
+description: Temporal.Calendar.prototype.daysInYear will take PlainDate and return
+  the number of days in a year.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slot, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInYear(temporalDateLike.[[ISOYear]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1995, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(1996, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1997, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1998, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1999, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(2000, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2001, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2002, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2003, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(2004, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2005, 7, 15)));
diff --git a/test/built-ins/Temporal/Calendar/prototype/days-in-year/string.js b/test/built-ins/Temporal/Calendar/prototype/days-in-year/string.js
new file mode 100644
index 0000000000..0af2ec2a1b
--- /dev/null
+++ b/test/built-ins/Temporal/Calendar/prototype/days-in-year/string.js
@@ -0,0 +1,50 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.calendar.prototype.daysinyear
+description: Temporal.Calendar.prototype.daysInYear will take PlainDate and return
+  the number of days in a year.
+info: |
+  1. Let calendar be the this value.
+  2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+  3. Assert: calendar.[[Identifier]] is "iso8601".
+  4. If Type(temporalDateLike) is not Object or temporalDateLike does not have an [[InitializedTemporalDate]] or [[InitializedTemporalYearMonth]] internal slot, then
+  a. Set temporalDateLike to ? ToTemporalDate(temporalDateLike).
+  5. Return 𝔽(! ISODaysInYear(temporalDateLike.[[ISOYear]])).
+features: [Temporal]
+---*/
+let cal = new Temporal.Calendar("iso8601");
+
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1995, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(1996, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1997, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1998, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(1999, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(2000, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2001, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2002, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2003, 7, 15)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDate(2004, 7, 15)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDate(2005, 7, 15)));
+
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1995, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(1996, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1997, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1998, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(1999, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(2000, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2001, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2002, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2003, 8, 23, 5, 30, 13)));
+assert.sameValue(366, cal.daysInYear(new Temporal.PlainDateTime(2004, 8, 23, 5, 30, 13)));
+assert.sameValue(365, cal.daysInYear(new Temporal.PlainDateTime(2005, 8, 23, 5, 30, 13)));
+
+assert.sameValue(365, cal.daysInYear("2019-03-18"));
+assert.sameValue(366, cal.daysInYear("2020-03-18"));
+assert.sameValue(365, cal.daysInYear("2021-03-18"));
+assert.sameValue(365, cal.daysInYear("2022-03-18"));
+assert.sameValue(365, cal.daysInYear("2023-03-18"));
+assert.sameValue(366, cal.daysInYear("2024-03-18"));
+assert.sameValue(365, cal.daysInYear("2025-03-18"));
+assert.sameValue(365, cal.daysInYear("2026-03-18"));