Temporal: Add TemporalHelpers.timeZoneObserver

Similar to the previous commit with property bags, many existing tests use
a Proxy to test the order of observable operations which involve user code
passed in as part of a Temporal.TimeZone object. I am going to write
several more tests that do this, as well. This seems like a good thing to
put into TemporalHelpers, where it can be implemented consistently so that
we don't get discrepancies in which operations are tracked.

Updates existing tests to use this helper.

harness/temporalHelpers.js

@@ -1635,6 +1635,44 @@ var TemporalHelpers = {
     return new SpringForwardFallBackTimeZone();
   },
 
+  /*
+   * timeZoneObserver:
+   * A custom calendar that behaves exactly like the UTC time zone but tracks
+   * calls to any of its methods, and Get/Has operations on its properties, by
+   * appending messages to an array. This is for the purpose of testing order of
+   * operations that are observable from user code. objectName is used in the
+   * log. methodOverrides is an optional object containing properties with the
+   * same name as Temporal.TimeZone methods. If the property value is a function
+   * it will be called with the proper arguments instead of the UTC method.
+   * Otherwise, the property value will be returned directly.
+   */
+  timeZoneObserver(calls, objectName, methodOverrides = {}) {
+    const utc = new Temporal.TimeZone("UTC");
+    const trackingMethods = {};
+    // Automatically generate the methods
+    ["getOffsetNanosecondsFor", "getPossibleInstantsFor", "toString"].forEach((methodName) => {
+      trackingMethods[methodName] = function (...args) {
+        actual.push(`call ${formatPropertyName(methodName, objectName)}`);
+        if (methodName in methodOverrides) {
+          const value = methodOverrides[methodName];
+          return typeof value === "function" ? value(...args) : value;
+        }
+        return utc[methodName](...args);
+      };
+    });
+    return new Proxy(trackingMethods, {
+      get(target, key, receiver) {
+        const result = Reflect.get(target, key, receiver);
+        actual.push(`get ${formatPropertyName(key, objectName)}`);
+        return result;
+      },
+      has(target, key) {
+        actual.push(`has ${formatPropertyName(key, objectName)}`);
+        return Reflect.has(target, key);
+      },
+    });
+  },
+
   /*
    * Returns an object that will append logs of any Gets or Calls of its valueOf
    * or toString properties to the array calls. Both valueOf and toString will

test/built-ins/Temporal/Instant/prototype/toString/timezone.js

@@ -18,28 +18,12 @@ const expected = [
 ];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456Z");
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  name: "Custom/TimeZone",
+  toString: TemporalHelpers.toPrimitiveObserver(actual, "Custom/TimeZone", "name"),
-
-  toString() {
-    actual.push("call timeZone.toString");
-    return TemporalHelpers.toPrimitiveObserver(actual, "Custom/TimeZone", "name");
-  },
-
   getOffsetNanosecondsFor(instantArg) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
     assert.sameValue(instantArg.epochNanoseconds, instant.epochNanoseconds);
     return -8735135801679;
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 Object.defineProperty(Temporal.TimeZone, "from", {

test/built-ins/Temporal/Instant/prototype/toZonedDateTime/plain-custom-timezone.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.instant.prototype.tozoneddatetime
 description: TimeZone.getPlainDateTimeFor is not called
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -14,22 +14,9 @@ const expected = [
 ];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
-const dateTime = Temporal.PlainDateTime.from("1963-07-02T12:00:00.987654321");
 const calendar = Temporal.Calendar.from("iso8601");
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  getPlainDateTimeFor() {
+  getPlainDateTimeFor: Temporal.PlainDateTime.from("1963-07-02T12:00:00.987654321"),
-    actual.push("call timeZone.getPlainDateTimeFor");
-    return dateTime;
-  }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const result = instant.toZonedDateTime({ timeZone, calendar });

test/built-ins/Temporal/Now/plainDate/toPlainDate-override.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.now.plaindate
 description: PlainDateTime.toPlainDate is not observably called
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -24,21 +24,11 @@ Object.defineProperty(Temporal.PlainDateTime.prototype, "toPlainDate", {
   },
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
     assert.sameValue(instant instanceof Temporal.Instant, true, "Instant");
     return 86399_999_999_999;
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const result = Temporal.Now.plainDate("iso8601", timeZone);

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

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.plaindatetime
 description: Behavior when provided calendar value is a function
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -16,21 +16,10 @@ const expected = [
 
 const calendar = function() {};
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
     return -Number(instant.epochNanoseconds % 86400000000000n);
-  }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
   },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
 
 Object.defineProperty(Temporal.Calendar, 'from', {

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

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.plaindatetime
 description: Observable interactions with the provided timezone-like object
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -16,10 +16,8 @@ const expected = [
   'call nestedTimeZone.getOffsetNanosecondsFor'
 ];
 
-const nestedTimeZone = new Proxy({
+const nestedTimeZone = TemporalHelpers.timeZoneObserver(actual, "nestedTimeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call nestedTimeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -28,24 +26,10 @@ const nestedTimeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has nestedTimeZone.${String(property)}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get nestedTimeZone.${String(property)}`);
-    return target[property];
-  }
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  timeZone: nestedTimeZone,
-
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -54,17 +38,8 @@ const timeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
+timeZone.timeZone = nestedTimeZone;
 
 Object.defineProperty(Temporal.TimeZone, 'from', {
   get() {

test/built-ins/Temporal/Now/plainDateTime/timezone.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.now.plaindatetime
 description: The value returned by TimeZone.getOffsetNanosecondsFor affects the result
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -15,21 +15,11 @@ const expected = [
   "call timeZone.getOffsetNanosecondsFor",
 ];
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
     assert.sameValue(instant instanceof Temporal.Instant, true, "Instant");
     return -Number(instant.epochNanoseconds % 86400_000_000_000n);
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const calendar = Temporal.Calendar.from("iso8601");

test/built-ins/Temporal/Now/plainDateTimeISO/timezone-object.js

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.plaindatetimeiso
 description: Observable interactions with the provided timezone-like object
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -16,10 +16,8 @@ const expected = [
   'call nestedTimeZone.getOffsetNanosecondsFor'
 ];
 
-const nestedTimeZone = new Proxy({
+const nestedTimeZone = TemporalHelpers.timeZoneObserver(actual, "nestedTimeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call nestedTimeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -28,24 +26,10 @@ const nestedTimeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has nestedTimeZone.${String(property)}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get nestedTimeZone.${String(property)}`);
-    return target[property];
-  }
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  timeZone: nestedTimeZone,
-
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -54,17 +38,8 @@ const timeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
+timeZone.timeZone = nestedTimeZone;
 
 Object.defineProperty(Temporal.TimeZone, 'from', {
   get() {

test/built-ins/Temporal/Now/plainTimeISO/timezone.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.now.plaintimeiso
 description: The value returned by TimeZone.getOffsetNanosecondsFor affects the result
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -15,21 +15,11 @@ const expected = [
   "call timeZone.getOffsetNanosecondsFor",
 ];
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
     assert.sameValue(instant instanceof Temporal.Instant, true, "Instant");
     return -Number(instant.epochNanoseconds % 86400_000_000_000n);
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const result = Temporal.Now.plainTimeISO(timeZone);

test/built-ins/Temporal/Now/plainTimeISO/toPlainTime-override.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.now.plaintimeiso
 description: PlainDateTime.toPlainTime is not observably called
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -24,21 +24,11 @@ Object.defineProperty(Temporal.PlainDateTime.prototype, "toPlainTime", {
   },
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
     assert.sameValue(instant instanceof Temporal.Instant, true, "Instant");
     return -Number(instant.epochNanoseconds % 86400_000_000_000n);
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const result = Temporal.Now.plainTimeISO(timeZone);

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

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.zoneddatetime
 description: Behavior when provided calendar value is a function
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -14,21 +14,10 @@ const expected = [
 
 const calendar = function() {};
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
 
 Object.defineProperty(Temporal.Calendar, 'from', {

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

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.zoneddatetime
 description: Observable interactions with the provided timezone-like object
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -14,10 +14,8 @@ const expected = [
   'has nestedTimeZone.timeZone'
 ];
 
-const nestedTimeZone = new Proxy({
+const nestedTimeZone = TemporalHelpers.timeZoneObserver(actual, "nestedTimeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call nestedTimeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -26,24 +24,10 @@ const nestedTimeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has nestedTimeZone.${String(property)}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get nestedTimeZone.${String(property)}`);
-    return target[property];
-  }
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  timeZone: nestedTimeZone,
-
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -52,17 +36,8 @@ const timeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
+timeZone.timeZone = nestedTimeZone;
 
 Object.defineProperty(Temporal.TimeZone, 'from', {
   get() {

test/built-ins/Temporal/Now/zonedDateTimeISO/timezone-object.js

@@ -3,7 +3,7 @@
 /*---
 esid: sec-temporal.now.zoneddatetime
 description: Observable interactions with the provided timezone-like object
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [BigInt, Proxy, Temporal]
 ---*/
 const actual = [];
@@ -14,10 +14,8 @@ const expected = [
   'has nestedTimeZone.timeZone'
 ];
 
-const nestedTimeZone = new Proxy({
+const nestedTimeZone = TemporalHelpers.timeZoneObserver(actual, "nestedTimeZone", {
   getOffsetNanosecondsFor(instant) {
-    actual.push('call nestedTimeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -26,24 +24,10 @@ const nestedTimeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has nestedTimeZone.${String(property)}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get nestedTimeZone.${String(property)}`);
-    return target[property];
-  }
 });
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  timeZone: nestedTimeZone,
-
   getOffsetNanosecondsFor(instant) {
-    actual.push('call timeZone.getOffsetNanosecondsFor');
-
     assert.sameValue(
       instant instanceof Temporal.Instant,
       true,
@@ -52,17 +36,8 @@ const timeZone = new Proxy({
 
     return -Number(instant.epochNanoseconds % 86400000000000n);
   }
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  }
 });
+timeZone.timeZone = nestedTimeZone;
 
 Object.defineProperty(Temporal.TimeZone, 'from', {
   get() {

test/built-ins/Temporal/PlainDateTime/prototype/toZonedDateTime/plain-custom-timezone.js

@@ -30,21 +30,11 @@ const instant = Temporal.Instant.fromEpochNanoseconds(-205156799012345679n);
 
 const options = TemporalHelpers.propertyBagObserver(actual, { disambiguation: "reject" }, "options");
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
   getPossibleInstantsFor(dateTimeArg) {
-    actual.push("call timeZone.getPossibleInstantsFor");
     assert.sameValue(dateTimeArg, dateTime);
     return [instant];
   },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const result = dateTime.toZonedDateTime(timeZone, options);

test/built-ins/Temporal/ZonedDateTime/prototype/toPlainDateTime/plain-custom-timezone.js

@@ -4,7 +4,7 @@
 /*---
 esid: sec-temporal.zoneddatetime.prototype.toplaindatetime
 description: timeZone.getOffsetNanosecondsFor() called
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
@@ -15,20 +15,8 @@ const expected = [
   "call timeZone.getOffsetNanosecondsFor",
 ];
 
-const timeZone = new Proxy({
+const timeZone = TemporalHelpers.timeZoneObserver(actual, "timeZone", {
-  getOffsetNanosecondsFor() {
+  getOffsetNanosecondsFor: -8735135802468,
-    actual.push("call timeZone.getOffsetNanosecondsFor");
-    return -8735135802468;
-  },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
 });
 
 const zdt = new Temporal.ZonedDateTime(160583136123456789n, timeZone);