Ensure that non-string TimeZone IDs will throw

This commit fills a test hole found by Codecov: we weren't checking for
the case of a custom time zone whose `id` property returns a non-string
value.

Note that the `id` property is only read in a few places, all on the
ZonedDateTime prototype: `until`, `since`, `equals`, `toString`,
`toLocaleString`, `toJSON`, and `timeZoneId`.

test/built-ins/Temporal/ZonedDateTime/prototype/equals/argument-propertybag-timezone-id-wrong-type.js

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.equals
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const datetime = new Temporal.ZonedDateTime(0n, "UTC");
+  assert.throws(TypeError, () => datetime.equals({ year: 1970, month: 1, day: 1, timeZone }));
+});

test/built-ins/Temporal/ZonedDateTime/prototype/since/argument-propertybag-timezone-id-wrong-type.js

@@ -0,0 +1,38 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.since
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, "UTC");
+  const properties = { year: 2004, month: 11, day: 9, hour: 11, minute: 33, second: 20, timeZone };
+  assert.throws(TypeError, () => datetime.since(properties, { largestUnit: "days" }));
+});

test/built-ins/Temporal/ZonedDateTime/prototype/timeZoneId/timezone-id-wrong-type.js

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.equals
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const zdt = Temporal.ZonedDateTime.from({ year: 1970, month: 1, day: 1, timeZone });
+  assert.throws(TypeError, () => zdt.timeZoneId);
+});

test/built-ins/Temporal/ZonedDateTime/prototype/toJSON/timezone-id-wrong-type.js

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.equals
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const zdt = Temporal.ZonedDateTime.from({ year: 1970, month: 1, day: 1, timeZone });
+  assert.throws(TypeError, () => zdt.toJSON());
+});

test/built-ins/Temporal/ZonedDateTime/prototype/toLocaleString/timezone-id-wrong-type.js

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.equals
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const zdt = Temporal.ZonedDateTime.from({ year: 1970, month: 1, day: 1, timeZone });
+  assert.throws(TypeError, () => zdt.toLocaleString());
+});

test/built-ins/Temporal/ZonedDateTime/prototype/toString/timezone-id-wrong-type.js

@@ -0,0 +1,37 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.equals
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const zdt = Temporal.ZonedDateTime.from({ year: 1970, month: 1, day: 1, timeZone });
+  assert.throws(TypeError, () => zdt.toString());
+});

test/built-ins/Temporal/ZonedDateTime/prototype/until/argument-propertybag-timezone-id-wrong-type.js

@@ -0,0 +1,38 @@
+// Copyright (C) 2023 Justin Grant. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.prototype.until
+description: TypeError thrown if time zone reports an id that is not a String
+features: [Temporal]
+---*/
+
+class CustomTimeZone extends Temporal.TimeZone {
+  constructor(id) {
+    super("UTC");
+    this._id = id;
+  }
+  get id() {
+    return this._id;
+  }
+}
+
+[
+  undefined,
+  null,
+  true,
+  -1000,
+  Symbol(),
+  3600_000_000_000n,
+  {},
+  {
+    valueOf() {
+      return 3600_000_000_000;
+    }
+  }
+].forEach((wrongId) => {
+  const timeZone = new CustomTimeZone(wrongId);
+  const datetime = new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, "UTC");
+  const properties = { year: 2004, month: 11, day: 9, hour: 11, minute: 33, second: 20, timeZone };
+  assert.throws(TypeError, () => datetime.until(properties, { largestUnit: "days" }));
+});