Validate required methods of Temporal Calendar protocol

Checking whether an object implements the Calendar protocol is now done by
means of HasProperty operations for each of the required methods unless
the object already has the Calendar brand.

Discussion:
https://github.com/tc39/proposal-temporal/issues/2104#issuecomment-1409549753

Corresponding normative PR:
https://github.com/tc39/proposal-temporal/pull/2485

harness/temporalHelpers.js

@@ -1464,6 +1464,34 @@ var TemporalHelpers = {
    * objectName is used in the log.
    */
   calendarObserver(calls, objectName, methodOverrides = {}) {
+    function removeExtraHasPropertyChecks(objectName, calls) {
+      // Inserting the tracking calendar into the return values of methods
+      // that we chain up into the ISO calendar for, causes extra HasProperty
+      // checks, which we observe. This removes them so that we don't leak
+      // implementation details of the helper into the test code.
+      assert.sameValue(calls.pop(), `has ${objectName}.yearOfWeek`);
+      assert.sameValue(calls.pop(), `has ${objectName}.yearMonthFromFields`);
+      assert.sameValue(calls.pop(), `has ${objectName}.year`);
+      assert.sameValue(calls.pop(), `has ${objectName}.weekOfYear`);
+      assert.sameValue(calls.pop(), `has ${objectName}.monthsInYear`);
+      assert.sameValue(calls.pop(), `has ${objectName}.monthDayFromFields`);
+      assert.sameValue(calls.pop(), `has ${objectName}.monthCode`);
+      assert.sameValue(calls.pop(), `has ${objectName}.month`);
+      assert.sameValue(calls.pop(), `has ${objectName}.mergeFields`);
+      assert.sameValue(calls.pop(), `has ${objectName}.inLeapYear`);
+      assert.sameValue(calls.pop(), `has ${objectName}.id`);
+      assert.sameValue(calls.pop(), `has ${objectName}.fields`);
+      assert.sameValue(calls.pop(), `has ${objectName}.daysInYear`);
+      assert.sameValue(calls.pop(), `has ${objectName}.daysInWeek`);
+      assert.sameValue(calls.pop(), `has ${objectName}.daysInMonth`);
+      assert.sameValue(calls.pop(), `has ${objectName}.dayOfYear`);
+      assert.sameValue(calls.pop(), `has ${objectName}.dayOfWeek`);
+      assert.sameValue(calls.pop(), `has ${objectName}.day`);
+      assert.sameValue(calls.pop(), `has ${objectName}.dateUntil`);
+      assert.sameValue(calls.pop(), `has ${objectName}.dateFromFields`);
+      assert.sameValue(calls.pop(), `has ${objectName}.dateAdd`);
+    }
+
     const iso8601 = new Temporal.Calendar("iso8601");
     const trackingMethods = {
       dateFromFields(...args) {
@@ -1475,7 +1503,9 @@ var TemporalHelpers = {
         const originalResult = iso8601.dateFromFields(...args);
         // Replace the calendar in the result with the call-tracking calendar
         const {isoYear, isoMonth, isoDay} = originalResult.getISOFields();
-        return new Temporal.PlainDate(isoYear, isoMonth, isoDay, this);
+        const result = new Temporal.PlainDate(isoYear, isoMonth, isoDay, this);
+        removeExtraHasPropertyChecks(objectName, calls);
+        return result;
       },
       yearMonthFromFields(...args) {
         calls.push(`call ${objectName}.yearMonthFromFields`);
@@ -1486,7 +1516,9 @@ var TemporalHelpers = {
         const originalResult = iso8601.yearMonthFromFields(...args);
         // Replace the calendar in the result with the call-tracking calendar
         const {isoYear, isoMonth, isoDay} = originalResult.getISOFields();
-        return new Temporal.PlainYearMonth(isoYear, isoMonth, this, isoDay);
+        const result = new Temporal.PlainYearMonth(isoYear, isoMonth, this, isoDay);
+        removeExtraHasPropertyChecks(objectName, calls);
+        return result;
       },
       monthDayFromFields(...args) {
         calls.push(`call ${objectName}.monthDayFromFields`);
@@ -1497,7 +1529,9 @@ var TemporalHelpers = {
         const originalResult = iso8601.monthDayFromFields(...args);
         // Replace the calendar in the result with the call-tracking calendar
         const {isoYear, isoMonth, isoDay} = originalResult.getISOFields();
-        return new Temporal.PlainMonthDay(isoMonth, isoDay, this, isoYear);
+        const result = new Temporal.PlainMonthDay(isoMonth, isoDay, this, isoYear);
+        removeExtraHasPropertyChecks(objectName, calls);
+        return result;
       },
       dateAdd(...args) {
         calls.push(`call ${objectName}.dateAdd`);
@@ -1507,12 +1541,34 @@ var TemporalHelpers = {
         }
         const originalResult = iso8601.dateAdd(...args);
         const {isoYear, isoMonth, isoDay} = originalResult.getISOFields();
-        return new Temporal.PlainDate(isoYear, isoMonth, isoDay, this);
+        const result = new Temporal.PlainDate(isoYear, isoMonth, isoDay, this);
+        removeExtraHasPropertyChecks(objectName, calls);
+        return result;
       },
       id: "iso8601",
     };
     // Automatically generate the other methods that don't need any custom code
-    ["toString", "dateUntil", "era", "eraYear", "year", "month", "monthCode", "day", "daysInMonth", "fields", "mergeFields"].forEach((methodName) => {
+    [
+      "dateUntil",
+      "day",
+      "dayOfWeek",
+      "dayOfYear",
+      "daysInMonth",
+      "daysInWeek",
+      "daysInYear",
+      "era",
+      "eraYear",
+      "fields",
+      "inLeapYear",
+      "mergeFields",
+      "month",
+      "monthCode",
+      "monthsInYear",
+      "toString",
+      "weekOfYear",
+      "year",
+      "yearOfWeek",
+    ].forEach((methodName) => {
       trackingMethods[methodName] = function (...args) {
         calls.push(`call ${formatPropertyName(methodName, objectName)}`);
         if (methodName in methodOverrides) {

test/built-ins/Temporal/Calendar/from/calendar-object.js

@@ -3,9 +3,33 @@
 
 /*---
 esid: sec-temporal.calendar.from
-description: Converting a plain object to Temporal.Calendar gives the same object
+description: >
+  Converting an object implementing the Calendar protocol to Temporal.Calendar
+  gives the same object
 features: [Temporal]
 ---*/
 
-const custom = { id: "custom-calendar" };
+const custom = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "custom-calendar",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
 assert.sameValue(Temporal.Calendar.from(custom), custom);

test/built-ins/Temporal/Calendar/from/calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -24,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/Calendar/prototype/dateAdd/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/dateAdd/order-of-operations.js

@@ -9,8 +9,29 @@ features: [Temporal]
 ---*/
 
 const expected = [
-  // ToTemporalDate → GetTemporalCalendarWithISODefault
+  // ToTemporalDate → GetTemporalCalendarSlotValueWithISODefault
   "get date.calendar",
+  "has date.calendar.dateAdd",
+  "has date.calendar.dateFromFields",
+  "has date.calendar.dateUntil",
+  "has date.calendar.day",
+  "has date.calendar.dayOfWeek",
+  "has date.calendar.dayOfYear",
+  "has date.calendar.daysInMonth",
+  "has date.calendar.daysInWeek",
+  "has date.calendar.daysInYear",
+  "has date.calendar.fields",
+  "has date.calendar.id",
+  "has date.calendar.inLeapYear",
+  "has date.calendar.mergeFields",
+  "has date.calendar.month",
+  "has date.calendar.monthCode",
+  "has date.calendar.monthDayFromFields",
+  "has date.calendar.monthsInYear",
+  "has date.calendar.weekOfYear",
+  "has date.calendar.year",
+  "has date.calendar.yearMonthFromFields",
+  "has date.calendar.yearOfWeek",
   // ToTemporalDate → CalendarFields
   "get date.calendar.fields",
   "call date.calendar.fields",

test/built-ins/Temporal/Calendar/prototype/dateUntil/argument-propertybag-calendar-wrong-type.js

@@ -18,7 +18,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -29,8 +28,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/dateUntil/order-of-operations.js

@@ -9,8 +9,29 @@ features: [Temporal]
 ---*/
 
 const expected = [
-  // ToTemporalDate 1 → GetTemporalCalendarWithISODefault
+  // ToTemporalDate 1 → GetTemporalCalendarSlotValueWithISODefault
   "get one.calendar",
+  "has one.calendar.dateAdd",
+  "has one.calendar.dateFromFields",
+  "has one.calendar.dateUntil",
+  "has one.calendar.day",
+  "has one.calendar.dayOfWeek",
+  "has one.calendar.dayOfYear",
+  "has one.calendar.daysInMonth",
+  "has one.calendar.daysInWeek",
+  "has one.calendar.daysInYear",
+  "has one.calendar.fields",
+  "has one.calendar.id",
+  "has one.calendar.inLeapYear",
+  "has one.calendar.mergeFields",
+  "has one.calendar.month",
+  "has one.calendar.monthCode",
+  "has one.calendar.monthDayFromFields",
+  "has one.calendar.monthsInYear",
+  "has one.calendar.weekOfYear",
+  "has one.calendar.year",
+  "has one.calendar.yearMonthFromFields",
+  "has one.calendar.yearOfWeek",
   // ToTemporalDate 1 → CalendarFields
   "get one.calendar.fields",
   "call one.calendar.fields",
@@ -30,8 +51,29 @@ const expected = [
   // ToTemporalDate 1 → CalendarDateFromFields
   "get one.calendar.dateFromFields",
   "call one.calendar.dateFromFields",
-  // ToTemporalDate 2 → GetTemporalCalendarWithISODefault
+  // ToTemporalDate 2 → GetTemporalCalendarSlotValueWithISODefault
   "get two.calendar",
+  "has two.calendar.dateAdd",
+  "has two.calendar.dateFromFields",
+  "has two.calendar.dateUntil",
+  "has two.calendar.day",
+  "has two.calendar.dayOfWeek",
+  "has two.calendar.dayOfYear",
+  "has two.calendar.daysInMonth",
+  "has two.calendar.daysInWeek",
+  "has two.calendar.daysInYear",
+  "has two.calendar.fields",
+  "has two.calendar.id",
+  "has two.calendar.inLeapYear",
+  "has two.calendar.mergeFields",
+  "has two.calendar.month",
+  "has two.calendar.monthCode",
+  "has two.calendar.monthDayFromFields",
+  "has two.calendar.monthsInYear",
+  "has two.calendar.weekOfYear",
+  "has two.calendar.year",
+  "has two.calendar.yearMonthFromFields",
+  "has two.calendar.yearOfWeek",
   // ToTemporalDate 2 → CalendarFields
   "get two.calendar.fields",
   "call two.calendar.fields",

test/built-ins/Temporal/Calendar/prototype/day/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/dayOfWeek/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/dayOfYear/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/daysInMonth/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/daysInWeek/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/daysInYear/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/inLeapYear/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/month/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/monthCode/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/monthsInYear/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/weekOfYear/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/year/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Calendar/prototype/yearOfWeek/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/Duration/compare/order-of-operations.js

@@ -88,6 +88,27 @@ actual.splice(0); // clear
 const expectedOpsForPlainRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",
@@ -153,6 +174,27 @@ actual.splice(0); // clear
 const expectedOpsForZonedRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",

test/built-ins/Temporal/Duration/prototype/add/order-of-operations.js

@@ -71,6 +71,27 @@ actual.splice(0); // clear
 const expectedOpsForPlainRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   // PrepareTemporalFields
@@ -135,6 +156,27 @@ actual.splice(0); // clear
 const expectedOpsForZonedRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   // PrepareTemporalFields

test/built-ins/Temporal/Duration/prototype/add/relativeto-propertybag-calendar-wrong-type.js

@@ -18,7 +18,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -28,7 +27,8 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
   [Temporal.PlainDate, "Temporal.PlainDate, object"],
   [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
   [Temporal.ZonedDateTime, "Temporal.ZonedDateTime, object"],

test/built-ins/Temporal/Duration/prototype/round/order-of-operations.js

@@ -48,6 +48,27 @@ const expectedOpsForPlainRelativeTo = [
   "call options.largestUnit.toString",
   "get options.relativeTo",
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",
@@ -230,6 +251,27 @@ const expectedOpsForZonedRelativeTo = [
   "call options.largestUnit.toString",
   "get options.relativeTo",
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",

test/built-ins/Temporal/Duration/prototype/round/relativeto-propertybag-calendar-wrong-type.js

@@ -18,7 +18,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -28,7 +27,8 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
   [Temporal.PlainDate, "Temporal.PlainDate, object"],
   [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
   [Temporal.ZonedDateTime, "Temporal.ZonedDateTime, object"],

test/built-ins/Temporal/Duration/prototype/subtract/order-of-operations.js

@@ -71,6 +71,27 @@ actual.splice(0); // clear
 const expectedOpsForPlainRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   // PrepareTemporalFields
@@ -135,6 +156,27 @@ actual.splice(0); // clear
 const expectedOpsForZonedRelativeTo = expected.concat([
   // ToRelativeTemporalObject
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   // PrepareTemporalFields

test/built-ins/Temporal/Duration/prototype/subtract/relativeto-propertybag-calendar-wrong-type.js

@@ -18,7 +18,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -28,7 +27,8 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
   [Temporal.PlainDate, "Temporal.PlainDate, object"],
   [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
   [Temporal.ZonedDateTime, "Temporal.ZonedDateTime, object"],

test/built-ins/Temporal/Duration/prototype/total/order-of-operations.js

@@ -36,6 +36,27 @@ const expectedOpsForPlainRelativeTo = [
   // ToRelativeTemporalObject
   "get options.relativeTo",
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",
@@ -143,6 +164,27 @@ const expectedOpsForZonedRelativeTo = [
   // ToRelativeTemporalObject
   "get options.relativeTo",
   "get options.relativeTo.calendar",
+  "has options.relativeTo.calendar.dateAdd",
+  "has options.relativeTo.calendar.dateFromFields",
+  "has options.relativeTo.calendar.dateUntil",
+  "has options.relativeTo.calendar.day",
+  "has options.relativeTo.calendar.dayOfWeek",
+  "has options.relativeTo.calendar.dayOfYear",
+  "has options.relativeTo.calendar.daysInMonth",
+  "has options.relativeTo.calendar.daysInWeek",
+  "has options.relativeTo.calendar.daysInYear",
+  "has options.relativeTo.calendar.fields",
+  "has options.relativeTo.calendar.id",
+  "has options.relativeTo.calendar.inLeapYear",
+  "has options.relativeTo.calendar.mergeFields",
+  "has options.relativeTo.calendar.month",
+  "has options.relativeTo.calendar.monthCode",
+  "has options.relativeTo.calendar.monthDayFromFields",
+  "has options.relativeTo.calendar.monthsInYear",
+  "has options.relativeTo.calendar.weekOfYear",
+  "has options.relativeTo.calendar.year",
+  "has options.relativeTo.calendar.yearMonthFromFields",
+  "has options.relativeTo.calendar.yearOfWeek",
   "get options.relativeTo.calendar.fields",
   "call options.relativeTo.calendar.fields",
   "get options.relativeTo.day",

test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-calendar-wrong-type.js

@@ -18,7 +18,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -28,7 +27,8 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
   [Temporal.PlainDate, "Temporal.PlainDate, object"],
   [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype, object"],
   [Temporal.ZonedDateTime, "Temporal.ZonedDateTime, object"],

test/built-ins/Temporal/Instant/prototype/toZonedDateTime/calendar-wrong-type.js

@@ -17,7 +17,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -26,6 +25,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/Now/plainDate/calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -24,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/Now/plainDateTime/calendar-function.js

@@ -17,6 +17,27 @@ const expected = [
 ];
 
 const calendar = function() {};
+calendar.dateAdd = () => {};
+calendar.dateFromFields = () => {};
+calendar.dateUntil = () => {};
+calendar.day = () => {};
+calendar.dayOfWeek = () => {};
+calendar.dayOfYear = () => {};
+calendar.daysInMonth = () => {};
+calendar.daysInWeek = () => {};
+calendar.daysInYear = () => {};
+calendar.fields = () => {};
+calendar.id = "test-calendar";
+calendar.inLeapYear = () => {};
+calendar.mergeFields = () => {};
+calendar.month = () => {};
+calendar.monthCode = () => {};
+calendar.monthDayFromFields = () => {};
+calendar.monthsInYear = () => {};
+calendar.weekOfYear = () => {};
+calendar.year = () => {};
+calendar.yearMonthFromFields = () => {};
+calendar.yearOfWeek = () => {};
 
 const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {

test/built-ins/Temporal/Now/plainDateTime/calendar-object.js

@@ -9,6 +9,29 @@ features: [Proxy, Temporal]
 ---*/
 
 const actual = [];
+const expected = [
+  "has calendar.dateAdd",
+  "has calendar.dateFromFields",
+  "has calendar.dateUntil",
+  "has calendar.day",
+  "has calendar.dayOfWeek",
+  "has calendar.dayOfYear",
+  "has calendar.daysInMonth",
+  "has calendar.daysInWeek",
+  "has calendar.daysInYear",
+  "has calendar.fields",
+  "has calendar.id",
+  "has calendar.inLeapYear",
+  "has calendar.mergeFields",
+  "has calendar.month",
+  "has calendar.monthCode",
+  "has calendar.monthDayFromFields",
+  "has calendar.monthsInYear",
+  "has calendar.weekOfYear",
+  "has calendar.year",
+  "has calendar.yearMonthFromFields",
+  "has calendar.yearOfWeek",
+];
 
 const calendar = TemporalHelpers.calendarObserver(actual, "calendar", {
   toString: "iso8601",
@@ -23,4 +46,4 @@ Object.defineProperty(Temporal.Calendar, 'from', {
 
 Temporal.Now.plainDateTime(calendar);
 
-assert.compareArray(actual, [], 'no observable operations should be invoked');
+assert.compareArray(actual, expected, 'order of observable operations');

test/built-ins/Temporal/Now/plainDateTime/calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -24,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/Now/zonedDateTime/calendar-function.js

@@ -14,6 +14,27 @@ const expected = [
 ];
 
 const calendar = function() {};
+calendar.dateAdd = () => {};
+calendar.dateFromFields = () => {};
+calendar.dateUntil = () => {};
+calendar.day = () => {};
+calendar.dayOfWeek = () => {};
+calendar.dayOfYear = () => {};
+calendar.daysInMonth = () => {};
+calendar.daysInWeek = () => {};
+calendar.daysInYear = () => {};
+calendar.fields = () => {};
+calendar.id = "test-calendar";
+calendar.inLeapYear = () => {};
+calendar.mergeFields = () => {};
+calendar.month = () => {};
+calendar.monthCode = () => {};
+calendar.monthDayFromFields = () => {};
+calendar.monthsInYear = () => {};
+calendar.weekOfYear = () => {};
+calendar.year = () => {};
+calendar.yearMonthFromFields = () => {};
+calendar.yearOfWeek = () => {};
 
 const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {

test/built-ins/Temporal/Now/zonedDateTime/calendar-object.js

@@ -9,6 +9,29 @@ features: [Proxy, Temporal]
 ---*/
 
 const actual = [];
+const expected = [
+  "has calendar.dateAdd",
+  "has calendar.dateFromFields",
+  "has calendar.dateUntil",
+  "has calendar.day",
+  "has calendar.dayOfWeek",
+  "has calendar.dayOfYear",
+  "has calendar.daysInMonth",
+  "has calendar.daysInWeek",
+  "has calendar.daysInYear",
+  "has calendar.fields",
+  "has calendar.id",
+  "has calendar.inLeapYear",
+  "has calendar.mergeFields",
+  "has calendar.month",
+  "has calendar.monthCode",
+  "has calendar.monthDayFromFields",
+  "has calendar.monthsInYear",
+  "has calendar.weekOfYear",
+  "has calendar.year",
+  "has calendar.yearMonthFromFields",
+  "has calendar.yearOfWeek",
+];
 
 const calendar = TemporalHelpers.calendarObserver(actual, "calendar", {
   toString: "iso8601",
@@ -23,4 +46,4 @@ Object.defineProperty(Temporal.Calendar, 'from', {
 
 Temporal.Now.zonedDateTime(calendar);
 
-assert.compareArray(actual, [], 'no observable operations should be invoked');
+assert.compareArray(actual, expected, 'order of observable operations');

test/built-ins/Temporal/Now/zonedDateTime/calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -24,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/PlainDate/calendar-wrong-type.js

@@ -23,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/PlainDate/compare/argument-propertybag-calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -26,8 +25,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDate/from/argument-propertybag-calendar-wrong-type.js

@@ -24,8 +24,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDate/from/order-of-operations.js

@@ -10,6 +10,27 @@ features: [Temporal]
 
 const expected = [
   "get fields.calendar",
+  "has fields.calendar.dateAdd",
+  "has fields.calendar.dateFromFields",
+  "has fields.calendar.dateUntil",
+  "has fields.calendar.day",
+  "has fields.calendar.dayOfWeek",
+  "has fields.calendar.dayOfYear",
+  "has fields.calendar.daysInMonth",
+  "has fields.calendar.daysInWeek",
+  "has fields.calendar.daysInYear",
+  "has fields.calendar.fields",
+  "has fields.calendar.id",
+  "has fields.calendar.inLeapYear",
+  "has fields.calendar.mergeFields",
+  "has fields.calendar.month",
+  "has fields.calendar.monthCode",
+  "has fields.calendar.monthDayFromFields",
+  "has fields.calendar.monthsInYear",
+  "has fields.calendar.weekOfYear",
+  "has fields.calendar.year",
+  "has fields.calendar.yearMonthFromFields",
+  "has fields.calendar.yearOfWeek",
   "get fields.calendar.fields",
   "call fields.calendar.fields",
   "get fields.day",

test/built-ins/Temporal/PlainDate/prototype/equals/argument-object-valid.js

@@ -11,6 +11,28 @@ const instance = new Temporal.PlainDate(2000, 5, 2);
 assert.sameValue(instance.equals({ year: 2000, month: 5, day: 2 }), true, "same date");
 assert.sameValue(instance.equals({ year: 2000, month: 5, day: 4 }), false, "different date");
 
-const calendar = { id: "a" };
+const calendar = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "a",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
 assert.sameValue(instance.withCalendar(calendar).equals({ year: 2000, month: 5, day: 2 }),
   false, "different calendar");

test/built-ins/Temporal/PlainDate/prototype/equals/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDate/prototype/equals/argument-string.js

@@ -11,5 +11,27 @@ const instance = new Temporal.PlainDate(2000, 5, 2);
 assert.sameValue(instance.equals("2000-05-02"), true, "same date");
 assert.sameValue(instance.equals("2000-05-04"), false, "different date");
 
-const calendar = { id: "a" };
+const calendar = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "a",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
 assert.sameValue(instance.withCalendar(calendar).equals("2000-05-02"), false, "different calendar");

test/built-ins/Temporal/PlainDate/prototype/since/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDate/prototype/since/calendar-mismatch.js

@@ -7,8 +7,52 @@ description: RangeError thrown if calendars' id properties do not match
 features: [Temporal]
 ---*/
 
-const calendar1 = { id: "A" };
+const calendar1 = {
-const calendar2 = { id: "B" };
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "A",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+const calendar2 = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "B",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
 
 const plainDate1 = new Temporal.PlainDate(2000, 1, 1, calendar1);
 const plainDate2 = new Temporal.PlainDate(2000, 1, 1, calendar2);

test/built-ins/Temporal/PlainDate/prototype/since/order-of-operations.js

@@ -11,6 +11,27 @@ features: [Temporal]
 const expected = [
   // ToTemporalDate
   "get other.calendar",
+  "has other.calendar.dateAdd",
+  "has other.calendar.dateFromFields",
+  "has other.calendar.dateUntil",
+  "has other.calendar.day",
+  "has other.calendar.dayOfWeek",
+  "has other.calendar.dayOfYear",
+  "has other.calendar.daysInMonth",
+  "has other.calendar.daysInWeek",
+  "has other.calendar.daysInYear",
+  "has other.calendar.fields",
+  "has other.calendar.id",
+  "has other.calendar.inLeapYear",
+  "has other.calendar.mergeFields",
+  "has other.calendar.month",
+  "has other.calendar.monthCode",
+  "has other.calendar.monthDayFromFields",
+  "has other.calendar.monthsInYear",
+  "has other.calendar.weekOfYear",
+  "has other.calendar.year",
+  "has other.calendar.yearMonthFromFields",
+  "has other.calendar.yearOfWeek",
   "get other.calendar.fields",
   "call other.calendar.fields",
   "get other.day",

test/built-ins/Temporal/PlainDate/prototype/toString/calendar-tostring.js

@@ -16,7 +16,27 @@ const customCalendar = {
   },
   toString() {
     TemporalHelpers.assertUnreachable('toString should not be called');
-  }
+  },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const date = new Temporal.PlainDate(2000, 5, 2, customCalendar);
 [

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-always.js

@@ -7,12 +7,35 @@ description: If calendarName is "always", the calendar ID should be included.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "2000-05-02[u-ca=iso8601]", "built-in ISO"],
-  [[{ id: "custom" }], "2000-05-02[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "2000-05-02[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "2000-05-02[u-ca=iso8601]", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "2000-05-02[u-ca=iso8601]", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-auto.js

@@ -7,12 +7,35 @@ description: If calendarName is "auto", "iso8601" should be omitted.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "2000-05-02", "built-in ISO"],
-  [[{ id: "custom" }], "2000-05-02[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "2000-05-02[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "2000-05-02", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "2000-05-02", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-critical.js

@@ -9,12 +9,35 @@ description: >
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "2000-05-02[!u-ca=iso8601]", "built-in ISO"],
-  [[{ id: "custom" }], "2000-05-02[!u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "2000-05-02[!u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "2000-05-02[!u-ca=iso8601]", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "2000-05-02[!u-ca=iso8601]", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "2000-05-02[!u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "2000-05-02[!u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "2000-05-02[!u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "2000-05-02[!u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-never.js

@@ -7,12 +7,35 @@ description: If calendarName is "never", the calendar ID should be omitted.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "2000-05-02", "built-in ISO"],
-  [[{ id: "custom" }], "2000-05-02", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "2000-05-02", "custom"],
-  [[{ id: "iso8601" }], "2000-05-02", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "2000-05-02", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "2000-05-02", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "2000-05-02", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "2000-05-02", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "2000-05-02", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-undefined.js

@@ -14,12 +14,35 @@ info: |
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "2000-05-02", "built-in ISO"],
-  [[{ id: "custom" }], "2000-05-02[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "2000-05-02[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "2000-05-02", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "2000-05-02", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "2000-05-02[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "2000-05-02[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDate/prototype/toString/calendarname-wrong-type.js

@@ -17,6 +17,26 @@ features: [Temporal]
 
 const calendar = {
   id: "custom",
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const date = new Temporal.PlainDate(2000, 5, 2, calendar);
 

test/built-ins/Temporal/PlainDate/prototype/toString/options-undefined.js

@@ -8,7 +8,27 @@ features: [Temporal]
 ---*/
 
 const calendar = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
   id: "custom",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const date1 = new Temporal.PlainDate(2000, 5, 2);
 const date2 = new Temporal.PlainDate(2000, 5, 2, calendar);

test/built-ins/Temporal/PlainDate/prototype/until/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDate/prototype/until/calendar-mismatch.js

@@ -7,8 +7,52 @@ description: RangeError thrown if calendars' id properties do not match
 features: [Temporal]
 ---*/
 
-const calendar1 = { id: "A" };
+const calendar1 = {
-const calendar2 = { id: "B" };
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "A",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+const calendar2 = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "B",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
 
 const plainDate1 = new Temporal.PlainDate(2000, 1, 1, calendar1);
 const plainDate2 = new Temporal.PlainDate(2000, 1, 1, calendar2);

test/built-ins/Temporal/PlainDate/prototype/until/order-of-operations.js

@@ -11,6 +11,27 @@ features: [Temporal]
 const expected = [
   // ToTemporalDate
   "get other.calendar",
+  "has other.calendar.dateAdd",
+  "has other.calendar.dateFromFields",
+  "has other.calendar.dateUntil",
+  "has other.calendar.day",
+  "has other.calendar.dayOfWeek",
+  "has other.calendar.dayOfYear",
+  "has other.calendar.daysInMonth",
+  "has other.calendar.daysInWeek",
+  "has other.calendar.daysInYear",
+  "has other.calendar.fields",
+  "has other.calendar.id",
+  "has other.calendar.inLeapYear",
+  "has other.calendar.mergeFields",
+  "has other.calendar.month",
+  "has other.calendar.monthCode",
+  "has other.calendar.monthDayFromFields",
+  "has other.calendar.monthsInYear",
+  "has other.calendar.weekOfYear",
+  "has other.calendar.year",
+  "has other.calendar.yearMonthFromFields",
+  "has other.calendar.yearOfWeek",
   "get other.calendar.fields",
   "call other.calendar.fields",
   "get other.day",

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-case-insensitive.js

@@ -7,7 +7,29 @@ description: Calendar names are case-insensitive
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "iSo8601";
 const result = instance.withCalendar(arg);

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-number.js

@@ -7,7 +7,29 @@ description: A number is converted to a string, then to Temporal.Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = 19761118;
 

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-string-leap-second.js

@@ -7,7 +7,29 @@ description: Leap second is a valid ISO string for Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "2016-12-31T23:59:60";
 const result = instance.withCalendar(arg);

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-string.js

@@ -7,7 +7,29 @@ description: A calendar ID is valid input for Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "iso8601";
 

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-temporal-object.js

@@ -31,7 +31,29 @@ const zonedDateTime = new Temporal.ZonedDateTime(1_000_000_000_000_000_000n, "UT
     },
   });
 
-  const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+  const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
   const result = instance.withCalendar(arg);
   assert.sameValue(result.getISOFields().calendar, calendar, "Temporal object coerced to calendar");
 

test/built-ins/Temporal/PlainDate/prototype/withCalendar/calendar-wrong-type.js

@@ -9,7 +9,29 @@ description: >
 features: [BigInt, Symbol, Temporal]
 ---*/
 
-const instance = new Temporal.PlainDate(1976, 11, 18, { id: "replace-me" });
+const instance = new Temporal.PlainDate(1976, 11, 18, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const rangeErrorTests = [
   [null, "null"],
@@ -17,7 +39,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -26,6 +47,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/PlainDate/prototype/withCalendar/subclassing-ignored.js

@@ -15,7 +15,24 @@ const customCalendar = {
   month() { return 2; },
   monthCode() { return "M02"; },
   day() { return 5; },
+  id: "custom-calendar",
   toString() { return "custom-calendar"; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 
 TemporalHelpers.checkSubclassingIgnored(

test/built-ins/Temporal/PlainDateTime/calendar-wrong-type.js

@@ -23,6 +23,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/PlainDateTime/compare/argument-propertybag-calendar-wrong-type.js

@@ -15,7 +15,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [calendar, description] of rangeErrorTests) {
@@ -26,8 +25,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/compare/calendar-ignored.js

@@ -4,11 +4,12 @@
 /*---
 esid: sec-temporal.plaindatetime.compare
 description: Calendar is not taken into account for the comparison.
+includes: [temporalHelpers.js]
 features: [Temporal]
 ---*/
 
-const calendar1 = { toString() { throw new Test262Error("should not call calendar1.toString") } };
+const calendar1 = TemporalHelpers.calendarThrowEverything();
-const calendar2 = { toString() { throw new Test262Error("should not call calendar2.toString") } };
+const calendar2 = TemporalHelpers.calendarThrowEverything();
 const dt1 = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, calendar1);
 const dt2 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar1);
 const dt3 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar1);

test/built-ins/Temporal/PlainDateTime/from/argument-propertybag-calendar-wrong-type.js

@@ -24,8 +24,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/from/order-of-operations.js

@@ -9,8 +9,29 @@ features: [Temporal]
 ---*/
 
 const expected = [
-  // GetTemporalCalendarWithISODefault
+  // GetTemporalCalendarSlotValueWithISODefault
   "get fields.calendar",
+  "has fields.calendar.dateAdd",
+  "has fields.calendar.dateFromFields",
+  "has fields.calendar.dateUntil",
+  "has fields.calendar.day",
+  "has fields.calendar.dayOfWeek",
+  "has fields.calendar.dayOfYear",
+  "has fields.calendar.daysInMonth",
+  "has fields.calendar.daysInWeek",
+  "has fields.calendar.daysInYear",
+  "has fields.calendar.fields",
+  "has fields.calendar.id",
+  "has fields.calendar.inLeapYear",
+  "has fields.calendar.mergeFields",
+  "has fields.calendar.month",
+  "has fields.calendar.monthCode",
+  "has fields.calendar.monthDayFromFields",
+  "has fields.calendar.monthsInYear",
+  "has fields.calendar.weekOfYear",
+  "has fields.calendar.year",
+  "has fields.calendar.yearMonthFromFields",
+  "has fields.calendar.yearOfWeek",
   // CalendarFields
   "get fields.calendar.fields",
   "call fields.calendar.fields",

test/built-ins/Temporal/PlainDateTime/prototype/equals/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/prototype/equals/calendar-checked.js

@@ -11,7 +11,28 @@ features: [Temporal]
 const actual = [];
 
 function makeCalendar(id, objectName) {
-  const calendar = {};
+  const calendar = {
+    dateAdd() {},
+    dateFromFields() {},
+    dateUntil() {},
+    day() {},
+    dayOfWeek() {},
+    dayOfYear() {},
+    daysInMonth() {},
+    daysInWeek() {},
+    daysInYear() {},
+    fields() {},
+    inLeapYear() {},
+    mergeFields() {},
+    month() {},
+    monthCode() {},
+    monthDayFromFields() {},
+    monthsInYear() {},
+    weekOfYear() {},
+    year() {},
+    yearMonthFromFields() {},
+    yearOfWeek() {},
+  };
   TemporalHelpers.observeProperty(actual, calendar, "id", id, objectName);
   return calendar;
 }
@@ -36,10 +57,50 @@ assert.sameValue(dt1.equals(dt3), false, "different calendar string");
 assert.compareArray(actual, ["get calendar1.id", "get calendar3.id"]);
 
 const calendar4 = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
   get id() { TemporalHelpers.assertUnreachable('should not get calendar4.id'); },
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const calendar5 = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
   get id() { TemporalHelpers.assertUnreachable('should not get calendar5.id'); },
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const dt4 = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, calendar4);
 const dt5 = new Temporal.PlainDateTime(2019, 10, 29, 10, 46, 38, 271, 986, 102, calendar4);

test/built-ins/Temporal/PlainDateTime/prototype/since/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/prototype/since/different-calendars-throws.js

@@ -8,7 +8,29 @@ features: [Temporal]
 ---*/
 
 const dt1 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0);
-const dt2 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0, { id: "custom" });
+const dt2 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "custom",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 assert.throws(
   RangeError,

test/built-ins/Temporal/PlainDateTime/prototype/since/order-of-operations.js

@@ -11,6 +11,27 @@ features: [Temporal]
 const expected = [
   // ToTemporalDateTime
   "get other.calendar",
+  "has other.calendar.dateAdd",
+  "has other.calendar.dateFromFields",
+  "has other.calendar.dateUntil",
+  "has other.calendar.day",
+  "has other.calendar.dayOfWeek",
+  "has other.calendar.dayOfYear",
+  "has other.calendar.daysInMonth",
+  "has other.calendar.daysInWeek",
+  "has other.calendar.daysInYear",
+  "has other.calendar.fields",
+  "has other.calendar.id",
+  "has other.calendar.inLeapYear",
+  "has other.calendar.mergeFields",
+  "has other.calendar.month",
+  "has other.calendar.monthCode",
+  "has other.calendar.monthDayFromFields",
+  "has other.calendar.monthsInYear",
+  "has other.calendar.weekOfYear",
+  "has other.calendar.year",
+  "has other.calendar.yearMonthFromFields",
+  "has other.calendar.yearOfWeek",
   "get other.calendar.fields",
   "call other.calendar.fields",
   "get other.day",

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendar-tostring.js

@@ -16,7 +16,27 @@ const customCalendar = {
   },
   toString() {
     TemporalHelpers.assertUnreachable('toString should not be called');
-  }
+  },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const date = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 56, 987, 654, 321, customCalendar);
 [

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-always.js

@@ -7,12 +7,35 @@ description: If calendarName is "always", the calendar ID should be included.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "1976-11-18T15:23:00[u-ca=iso8601]", "built-in ISO"],
-  [[{ id: "custom" }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "1976-11-18T15:23:00[u-ca=iso8601]", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=iso8601]", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-auto.js

@@ -7,12 +7,35 @@ description: If calendarName is "auto", "iso8601" should be omitted.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "1976-11-18T15:23:00", "built-in ISO"],
-  [[{ id: "custom" }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "1976-11-18T15:23:00", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "1976-11-18T15:23:00", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-critical.js

@@ -9,12 +9,35 @@ description: >
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "1976-11-18T15:23:00[!u-ca=iso8601]", "built-in ISO"],
-  [[{ id: "custom" }], "1976-11-18T15:23:00[!u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "1976-11-18T15:23:00[!u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "1976-11-18T15:23:00[!u-ca=iso8601]", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "1976-11-18T15:23:00[!u-ca=iso8601]", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "1976-11-18T15:23:00[!u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "1976-11-18T15:23:00[!u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "1976-11-18T15:23:00[!u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "1976-11-18T15:23:00[!u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-never.js

@@ -7,12 +7,35 @@ description: If calendarName is "never", the calendar ID should be omitted.
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "1976-11-18T15:23:00", "built-in ISO"],
-  [[{ id: "custom" }], "1976-11-18T15:23:00", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "1976-11-18T15:23:00", "custom"],
-  [[{ id: "iso8601" }], "1976-11-18T15:23:00", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "1976-11-18T15:23:00", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "1976-11-18T15:23:00", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "1976-11-18T15:23:00", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "1976-11-18T15:23:00", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "1976-11-18T15:23:00", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-undefined.js

@@ -14,12 +14,35 @@ info: |
 features: [Temporal]
 ---*/
 
+const calendarMethods = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+};
+
 const tests = [
   [[], "1976-11-18T15:23:00", "built-in ISO"],
-  [[{ id: "custom" }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
+  [[{ id: "custom", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=custom]", "custom"],
-  [[{ id: "iso8601" }], "1976-11-18T15:23:00", "custom with iso8601 id"],
+  [[{ id: "iso8601", ...calendarMethods }], "1976-11-18T15:23:00", "custom with iso8601 id"],
-  [[{ id: "ISO8601" }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
+  [[{ id: "ISO8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=ISO8601]", "custom with caps id"],
-  [[{ id: "\u0131so8601" }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
+  [[{ id: "\u0131so8601", ...calendarMethods }], "1976-11-18T15:23:00[u-ca=\u0131so8601]", "custom with dotless i id"],
 ];
 
 for (const [args, expected, description] of tests) {

test/built-ins/Temporal/PlainDateTime/prototype/toString/calendarname-wrong-type.js

@@ -17,6 +17,26 @@ features: [Temporal]
 
 const calendar = {
   id: "custom",
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const datetime = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 56, 987, 654, 321, calendar);
 

test/built-ins/Temporal/PlainDateTime/prototype/toString/options-undefined.js

@@ -8,7 +8,27 @@ features: [Temporal]
 ---*/
 
 const calendar = {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
   id: "custom",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const datetime1 = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 56, 987, 650, 0);
 const datetime2 = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 56, 987, 650, 0, calendar);

test/built-ins/Temporal/PlainDateTime/prototype/until/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/prototype/until/different-calendars-throws.js

@@ -8,7 +8,29 @@ features: [Temporal]
 ---*/
 
 const dt1 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0);
-const dt2 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0, { id: "custom" });
+const dt2 = new Temporal.PlainDateTime(2000, 1, 1, 0, 0, 0, 0, 0, 0, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "custom",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 assert.throws(
   RangeError,

test/built-ins/Temporal/PlainDateTime/prototype/until/order-of-operations.js

@@ -11,6 +11,27 @@ features: [Temporal]
 const expected = [
   // ToTemporalDateTime
   "get other.calendar",
+  "has other.calendar.dateAdd",
+  "has other.calendar.dateFromFields",
+  "has other.calendar.dateUntil",
+  "has other.calendar.day",
+  "has other.calendar.dayOfWeek",
+  "has other.calendar.dayOfYear",
+  "has other.calendar.daysInMonth",
+  "has other.calendar.daysInWeek",
+  "has other.calendar.daysInYear",
+  "has other.calendar.fields",
+  "has other.calendar.id",
+  "has other.calendar.inLeapYear",
+  "has other.calendar.mergeFields",
+  "has other.calendar.month",
+  "has other.calendar.monthCode",
+  "has other.calendar.monthDayFromFields",
+  "has other.calendar.monthsInYear",
+  "has other.calendar.weekOfYear",
+  "has other.calendar.year",
+  "has other.calendar.yearMonthFromFields",
+  "has other.calendar.yearOfWeek",
   "get other.calendar.fields",
   "call other.calendar.fields",
   "get other.day",

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/argument-string.js

@@ -9,7 +9,28 @@ includes: [temporalHelpers.js]
 ---*/
 
 const calendar = {
-  toString() { return "something special"; }
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "something special",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  toString() { return "something special"; },
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const dt = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, calendar);
 const result = dt.withCalendar("iso8601");

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-case-insensitive.js

@@ -7,7 +7,29 @@ description: Calendar names are case-insensitive
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "iSo8601";
 const result = instance.withCalendar(arg);

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-number.js

@@ -7,7 +7,29 @@ description: A number is converted to a string, then to Temporal.Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = 19761118;
 

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-string-leap-second.js

@@ -7,7 +7,29 @@ description: Leap second is a valid ISO string for Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "2016-12-31T23:59:60";
 const result = instance.withCalendar(arg);

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-string.js

@@ -7,7 +7,29 @@ description: A calendar ID is valid input for Calendar
 features: [Temporal]
 ---*/
 
-const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const arg = "iso8601";
 

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-temporal-object.js

@@ -31,7 +31,29 @@ const zonedDateTime = new Temporal.ZonedDateTime(1_000_000_000_000_000_000n, "UT
     },
   });
 
-  const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+  const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
   const result = instance.withCalendar(arg);
   assert.sameValue(result.getISOFields().calendar, calendar, "Temporal object coerced to calendar");
 

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-wrong-type.js

@@ -9,7 +9,29 @@ description: >
 features: [BigInt, Symbol, Temporal]
 ---*/
 
-const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, { id: "replace-me" });
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, {
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  id: "replace-me",
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
+});
 
 const rangeErrorTests = [
   [null, "null"],
@@ -17,7 +39,6 @@ const rangeErrorTests = [
   ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
-  [new Temporal.TimeZone("UTC"), "time zone instance"],
 ];
 
 for (const [arg, description] of rangeErrorTests) {
@@ -26,6 +47,9 @@ for (const [arg, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
+  [{}, "plain object that doesn't implement the protocol"],
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
 ];
 
 for (const [arg, description] of typeErrorTests) {

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/subclassing-ignored.js

@@ -15,7 +15,24 @@ const customCalendar = {
   month() { return 2; },
   monthCode() { return "M02"; },
   day() { return 5; },
+  id: "custom-calendar",
   toString() { return "custom-calendar"; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 
 TemporalHelpers.checkSubclassingIgnored(

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-noniso.js

@@ -16,7 +16,23 @@ const cal = {
   year() { return 2008; },
   month() { return 9; },
   monthCode() { return "M09"; },
-  day() { return 6; }
+  day() { return 6; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const pdt = new Temporal.PlainDateTime(1995, 12, 7, 3, 24, 30, 0, 0, 0);
 assert.sameValue(pdt.calendarId, "iso8601", "PlainDateTime with ISO calendar");

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-id.js

@@ -10,7 +10,27 @@ includes: [temporalHelpers.js]
 
 const cal1 = {
   id: "this is a string",
-  toString() { return "this is another string"; }
+  toString() { return "this is another string"; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  day() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  month() {},
+  monthCode() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  year() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const cal2 = {
   id: "this is a string",
@@ -20,7 +40,23 @@ const cal2 = {
   year() { return 2008; },
   month() { return 9; },
   monthCode() { return "M09"; },
-  day() { return 6; }
+  day() { return 6; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const pdt = new Temporal.PlainDateTime(1995, 12, 7, 3, 24, 30, 0, 0, 0, cal1);
 const pd = new Temporal.PlainDate(2010, 11, 12, cal2);

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-object.js

@@ -20,7 +20,23 @@ const cal = {
   year() { return 2008; },
   month() { return 9; },
   monthCode() { return "M09"; },
-  day() { return 6; }
+  day() { return 6; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const pdt = new Temporal.PlainDateTime(1995, 12, 7, 3, 24, 30, 0, 0, 0, cal);
 const pd = new Temporal.PlainDate(2010, 11, 12, cal);

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar.js

@@ -16,7 +16,23 @@ const cal = {
   year() { return 2008; },
   month() { return 9; },
   monthCode() { return "M09"; },
-  day() { return 6; }
+  day() { return 6; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const pdt = new Temporal.PlainDateTime(1995, 12, 7, 3, 24, 30, 0, 0, 0, cal);
 const pd = new Temporal.PlainDate(2010, 11, 12);

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-propertybag-calendar-wrong-type.js

@@ -27,8 +27,9 @@ for (const [calendar, description] of rangeErrorTests) {
 
 const typeErrorTests = [
   [Symbol(), "symbol"],
-  [{}, "plain object"],  // TypeError due to missing dateFromFields()
+  [{}, "plain object that doesn't implement the protocol"],
-  [Temporal.Calendar, "Temporal.Calendar, object"],  // ditto
+  [new Temporal.TimeZone("UTC"), "time zone instance"],
+  [Temporal.Calendar, "Temporal.Calendar, object"],
   [Temporal.Calendar.prototype, "Temporal.Calendar.prototype, object"],  // fails brand check in dateFromFields()
 ];
 

test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-string-iso-calendar.js

@@ -16,7 +16,23 @@ const cal = {
   year() { return 2008; },
   month() { return 9; },
   monthCode() { return "M09"; },
-  day() { return 6; }
+  day() { return 6; },
+  dateAdd() {},
+  dateFromFields() {},
+  dateUntil() {},
+  dayOfWeek() {},
+  dayOfYear() {},
+  daysInMonth() {},
+  daysInWeek() {},
+  daysInYear() {},
+  fields() {},
+  inLeapYear() {},
+  mergeFields() {},
+  monthDayFromFields() {},
+  monthsInYear() {},
+  weekOfYear() {},
+  yearMonthFromFields() {},
+  yearOfWeek() {},
 };
 const dt = new Temporal.PlainDateTime(1995, 12, 7, 3, 24, 30, 0, 0, 0, cal);
 const shifted = dt.withPlainDate("2010-11-12");