`String.prototype.isWellFormed`/`String.prototype.toWellFormed`: add tests

features.txt

@@ -292,6 +292,11 @@ change-array-by-copy
 # https://tc39.es/proposal-array-from-async/
 Array.fromAsync
 
+# Well-formed Unicode strings
+# https://github.com/tc39/proposal-is-usv-string
+String.prototype.isWellFormed
+String.prototype.toWellFormed
+
 ## Standard language features
 #
 # Language features that have been included in a published version of the

test/built-ins/String/prototype/isWellFormed/length.js

@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  String.prototype.isWellFormed.length value and descriptor.
+info: |
+  String.prototype.isWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+features: [String.prototype.isWellFormed]
+---*/
+
+verifyProperty(String.prototype.isWellFormed, 'length', {
+  configurable: true,
+  enumerable: false,
+  writable: false,
+  value: 0
+});

test/built-ins/String/prototype/isWellFormed/name.js

@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  String.prototype.isWellFormed.name value and descriptor.
+info: |
+  String.prototype.isWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+features: [String.prototype.isWellFormed]
+---*/
+
+verifyProperty(String.prototype.isWellFormed, 'name', {
+  enumerable: false,
+  writable: false,
+  configurable: true,
+  value: 'isWellFormed'
+});

test/built-ins/String/prototype/isWellFormed/not-a-constructor.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  String.prototype.includes does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [String.prototype.isWellFormed, Reflect.construct]
+---*/
+
+assert.sameValue(
+  isConstructor(String.prototype.isWellFormed),
+  false,
+  'isConstructor(String.prototype.isWellFormed) must return false'
+);
+
+assert.throws(TypeError, function () {
+  new String.prototype.isWellFormed();
+}, '`new String.prototype.isWellFormed()` throws TypeError');

test/built-ins/String/prototype/isWellFormed/prop-desc.js

@@ -0,0 +1,26 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  Property type and descriptor.
+info: |
+  String.prototype.isWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+includes: [propertyHelper.js]
+features: [String.prototype.isWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.isWellFormed, 'function');
+
+assert.sameValue(
+  typeof String.prototype.isWellFormed,
+  'function',
+  'The value of `typeof String.prototype.isWellFormed` is "function"'
+);
+
+verifyProperty(String.prototype, 'isWellFormed', {
+  enumerable: false,
+  writable: true,
+  configurable: true
+});

test/built-ins/String/prototype/isWellFormed/return-abrupt-from-this.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  Return abrupt from RequireObjectCoercible(this value).
+info: |
+  String.prototype.isWellFormed( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+
+features: [String.prototype.isWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.isWellFormed, 'function');
+
+assert.throws(TypeError, function () {
+  String.prototype.isWellFormed.call(undefined);
+}, '`String.prototype.isWellFormed.call(undefined)` throws TypeError');
+
+assert.throws(TypeError, function () {
+  String.prototype.isWellFormed.call(null);
+}, '`String.prototype.isWellFormed.call(null)` throws TypeError');

test/built-ins/String/prototype/isWellFormed/returns-boolean.js

@@ -0,0 +1,44 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  The method should return a boolean.
+info: |
+  String.prototype.isWellFormed ( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+  2. Let S be ? ToString(O).
+  3. Return IsStringWellFormedUnicode(S).
+
+features: [String.prototype.isWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.isWellFormed, 'function');
+
+var leadingPoo = '\uD83D';
+var trailingPoo = '\uDCA9';
+var wholePoo = leadingPoo + trailingPoo;
+
+assert.sameValue(
+  ('a' + leadingPoo + 'c' + leadingPoo + 'e').isWellFormed(),
+  false,
+  'lone leading surrogates are not well-formed'
+);
+assert.sameValue(
+  ('a' + trailingPoo + 'c' + trailingPoo + 'e').isWellFormed(),
+  false,
+  'lone trailing surrogates are not well-formed'
+);
+assert.sameValue(
+  ('a' + trailingPoo + leadingPoo + 'd').isWellFormed(),
+  false,
+  'a wrong-ordered surrogate pair is not well-formed'
+)
+
+assert.sameValue('a💩c'.isWellFormed(), true, 'a surrogate pair using a literal code point is well-formed');
+assert.sameValue('a\uD83D\uDCA9c'.isWellFormed(), true, 'a surrogate pair formed by escape sequences is well-formed');
+assert.sameValue(('a' + leadingPoo + trailingPoo + 'd').isWellFormed(), true, 'a surrogate pair formed by concatenation is well-formed');
+assert.sameValue(wholePoo.slice(0, 1).isWellFormed(), false, 'a surrogate pair sliced to the leading surrogate is not well-formed');
+assert.sameValue(wholePoo.slice(1).isWellFormed(), false, 'a surrogate pair sliced to the trailing surrogate is not well-formed');
+assert.sameValue('abc'.isWellFormed(), true, 'a latin-1 string is well-formed');
+assert.sameValue('a\u25A8c'.isWellFormed(), true, 'a non-ASCII character is well-formed');

test/built-ins/String/prototype/isWellFormed/to-string.js

@@ -0,0 +1,27 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.iswellformed
+description: >
+  The method should coerce the receiver to a string.
+info: |
+  String.prototype.isWellFormed ( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+  2. Let S be ? ToString(O).
+  3. Return IsStringWellFormedUnicode(S).
+
+features: [String.prototype.isWellFormed]
+---*/
+
+var obj = {
+    toString: function () {
+        throw new Test262Error('calls ToString');
+    }
+};
+
+asserts.throws(
+    function () { String.prototype.isWellFormed.call(obj); },
+    Test262Error,
+    'coerces the receiver to a string'
+);

test/built-ins/String/prototype/toWellFormed/length.js

@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  String.prototype.toWellFormed.length value and descriptor.
+info: |
+  String.prototype.toWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+features: [String.prototype.toWellFormed]
+---*/
+
+verifyProperty(String.prototype.toWellFormed, 'length', {
+  configurable: true,
+  enumerable: false,
+  writable: false,
+  value: 0
+});

test/built-ins/String/prototype/toWellFormed/name.js

@@ -0,0 +1,21 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  String.prototype.toWellFormed.name value and descriptor.
+info: |
+  String.prototype.toWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+features: [String.prototype.toWellFormed]
+---*/
+
+verifyProperty(String.prototype.toWellFormed, 'name', {
+  enumerable: false,
+  writable: false,
+  configurable: true,
+  value: 'isWellFormed'
+});

test/built-ins/String/prototype/toWellFormed/not-a-constructor.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  String.prototype.includes does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [String.prototype.toWellFormed, Reflect.construct]
+---*/
+
+assert.sameValue(
+  isConstructor(String.prototype.toWellFormed),
+  false,
+  'isConstructor(String.prototype.toWellFormed) must return false'
+);
+
+assert.throws(TypeError, function () {
+  new String.prototype.toWellFormed();
+}, '`new String.prototype.toWellFormed()` throws TypeError');

test/built-ins/String/prototype/toWellFormed/prop-desc.js

@@ -0,0 +1,26 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  Property type and descriptor.
+info: |
+  String.prototype.toWellFormed( )
+
+  17 ECMAScript Standard Built-in Objects
+includes: [propertyHelper.js]
+features: [String.prototype.toWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.toWellFormed, 'function');
+
+assert.sameValue(
+  typeof String.prototype.isWellFormed,
+  'function',
+  'The value of `typeof String.prototype.toWellFormed` is "function"'
+);
+
+verifyProperty(String.prototype, 'toWellFormed', {
+  enumerable: false,
+  writable: true,
+  configurable: true
+});

test/built-ins/String/prototype/toWellFormed/return-abrupt-from-this.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  Return abrupt from RequireObjectCoercible(this value).
+info: |
+  String.prototype.toWellFormed( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+
+features: [String.prototype.toWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.toWellFormed, 'function');
+
+assert.throws(TypeError, function () {
+  String.prototype.toWellFormed.call(undefined);
+}, '`String.prototype.toWellFormed.call(undefined)` throws TypeError');
+
+assert.throws(TypeError, function () {
+  String.prototype.toWellFormed.call(null);
+}, '`String.prototype.toWellFormed.call(null)` throws TypeError');

test/built-ins/String/prototype/toWellFormed/returns-well-formed-string.js

@@ -0,0 +1,55 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  The method should return a well-formed string.
+info: |
+  String.prototype.toWellFormed ( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+  2. Let S be ? ToString(O).
+  3. Let strLen be the length of S.
+  4. Let k be 0.
+  5. Let result be the empty String.
+  6. Repeat, while k < strLen,
+    a. Let cp be CodePointAt(S, k).
+    b. If cp.[[IsUnpairedSurrogate]] is true, then
+      i. Set result to the string-concatenation of result and 0xFFFD (REPLACEMENT CHARACTER).
+    c. Else,
+      i. Set result to the string-concatenation of result and UTF16EncodeCodePoint(cp.[[CodePoint]]).
+    d. Set k to k + cp.[[CodeUnitCount]].
+  7. Return result.
+
+features: [String.prototype.toWellFormed]
+---*/
+assert.sameValue(typeof String.prototype.toWellFormed, 'function');
+
+var replacementChar = '\uFFFD';
+var leadingPoo = '\uD83D';
+var trailingPoo = '\uDCA9';
+var wholePoo = leadingPoo + trailingPoo;
+
+assert.sameValue(
+  ('a' + leadingPoo + 'c' + leadingPoo + 'e').toWellFormed(),
+  'a' + replacementChar + 'c' + replacementChar + 'e',
+  'lone leading surrogates are replaced with the expected replacement character'
+);
+assert.sameValue(
+  ('a' + trailingPoo + 'c' + trailingPoo + 'e').toWellFormed(),
+  'a' + replacementChar + 'c' + replacementChar + 'e',
+  'lone trailing surrogates are replaced with the expected replacement character'
+);
+assert.sameValue(
+  ('a' + trailingPoo + leadingPoo + 'd').toWellFormed(),
+  'a' + replacementChar + replacementChar + 'd',
+  'a wrong-ordered surrogate pair is replaced with two replacement characters'
+)
+
+assert.sameValue('a💩c'.toWellFormed(), 'a💩c', 'a surrogate pair using a literal code point is already well-formed');
+assert.sameValue('a\uD83D\uDCA9c'.toWellFormed(), 'a\uD83D\uDCA9c', 'a surrogate pair formed by escape sequences is already well-formed');
+assert.sameValue(('a' + leadingPoo + trailingPoo + 'd').toWellFormed(), 'a' + wholePoo + 'd', 'a surrogate pair formed by concatenation is already well-formed');
+assert.sameValue(wholePoo.slice(0, 1).toWellFormed(), replacementChar, 'a surrogate pair sliced to the leading surrogate is replaced with the expected replacement character');
+assert.sameValue(wholePoo.slice(1).toWellFormed(), replacementChar, 'a surrogate pair sliced to the trailing surrogate is replaced with the expected replacement character');
+assert.sameValue('abc'.toWellFormed(), 'abc', 'a latin-1 string is already well-formed');
+assert.sameValue('a\u25A8c'.toWellFormed(), 'a\u25A8c', 'a string with a non-ASCII character is already well-formed');

test/built-ins/String/prototype/toWellFormed/to-string.js

@@ -0,0 +1,27 @@
+// Copyright (C) 2022 Jordan Harband. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-string.prototype.towellformed
+description: >
+  The method should coerce the receiver to a string.
+info: |
+  String.prototype.toWellFormed ( )
+
+  1. Let O be ? RequireObjectCoercible(this value).
+  2. Let S be ? ToString(O).
+  …
+
+features: [String.prototype.toWellFormed]
+---*/
+
+var obj = {
+    toString: function () {
+        throw new Test262Error('calls ToString');
+    }
+};
+
+asserts.throws(
+    function () { String.prototype.toWellFormed.call(obj); },
+    Test262Error,
+    'coerces the receiver to a string'
+);