Add Set.prototype.union tests (#3816)

* Beginning of adding Set.prototype.union tests

* Fix description

* Add tests for GetSetRecord

Which also allows Set-like objects

* Add title to test descriptions

* Add test for ensuring values are appended

* Add tests for properties of union

Also: tests for RequireInternalSlot, Constructor, BuiltIns.

Added a test to ensure that -0F is converted to +0F

* Ensure Set.prototype.add is not called as part of .union

* fix lint issues

* Set subclassing and Symbol.species tests

* Set.prototype.union tests for arrays and subclass methods

* Add the Set-methods frontmatter feature flag

* Add additional Set.prototype.union test for edge cases

* Update test/built-ins/Set/GetSetRecord/keys-is-callable.js

Co-authored-by: Kevin Gibbons <bakkot@gmail.com>

* Use compareArray() for assertions

* Remove class field syntax

* Remove unused args

* Update test/built-ins/Set/prototype/union/subclass-receiver-methods.js

Co-authored-by: Jordan Harband <ljharb@gmail.com>

* Return original 'add'

* address comments

* add one more mutation in the evil mutating iterator test

* address further comments

---------

Co-authored-by: Kevin Gibbons <bakkot@gmail.com>
Co-authored-by: Jordan Harband <ljharb@gmail.com>
Co-authored-by: Ms2ger <Ms2ger@igalia.com>

features.txt

@@ -210,6 +210,7 @@ regexp-named-groups
 regexp-unicode-property-escapes
 rest-parameters
 Set
+Set-methods
 SharedArrayBuffer
 string-trimming
 String.fromCodePoint

test/built-ins/Set/prototype/union/add-not-called.js

@@ -0,0 +1,27 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union should not call Set.prototype.add
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = new Set([2, 3]);
+const expected = [1, 2, 3];
+
+const originalAdd = Set.prototype.add;
+let count = 0;
+Set.prototype.add = function (...rest) {
+  count++;
+  return originalAdd.apply(this, rest);
+};
+
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
+assert.sameValue(count, 0, "Add is never called");
+
+Set.prototype.add = originalAdd;

test/built-ins/Set/prototype/union/allows-set-like-class.js

@@ -0,0 +1,34 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: GetSetRecord allows instances of Set-like classes
+info: |
+    1. If obj is not an Object, throw a TypeError exception.
+    2. Let rawSize be ? Get(obj, "size").
+    ...
+    7. Let has be ? Get(obj, "has").
+    ...
+    9. Let keys be ? Get(obj, "keys").
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = new class {
+  get size() {
+    return 2;
+  }
+  has() {
+    throw new Test262Error("Set.prototype.union should not invoke .has on its argument");
+  }
+  * keys() {
+    yield 2;
+    yield 3;
+  }
+};
+const expected = [1, 2, 3];
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/allows-set-like-object.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: GetSetRecord allows Set-like objects
+info: |
+    1. If obj is not an Object, throw a TypeError exception.
+    2. Let rawSize be ? Get(obj, "size").
+    ...
+    7. Let has be ? Get(obj, "has").
+    ...
+    9. Let keys be ? Get(obj, "keys").
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = {
+  size: 2,
+  has: () => {},
+  keys: function* keys() {
+    yield 2;
+    yield 3;
+  },
+};
+const expected = [1, 2, 3];
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/appends-new-values.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union appends new values to a copy of the original Set
+info: |
+    7.b.iii.1 Append nextValue to resultSetData.
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = new Set([-1, 0, 3]);
+const expected = [1, 2, -1, 0, 3];
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
+
+const s3 = new Set([1, 2, -3]);
+const s4 = new Set([-1, 0]);
+const expected2 = [1, 2, -3, -1, 0];
+const combined2 = s3.union(s4);
+
+assert.compareArray([...combined2], expected2);
+assert.sameValue(
+  combined2 instanceof Set,
+  true,
+  "The returned object is a Set"
+);

test/built-ins/Set/prototype/union/array-throws.js

@@ -0,0 +1,17 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union doesn't work with arrays
+features: [Set-methods]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = [3];
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(s2);
+  },
+  "Throws an error when an array is used"
+);

test/built-ins/Set/prototype/union/builtins.js

@@ -0,0 +1,25 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Tests that Set.prototype.union meets the requirements for built-in objects
+features: [Set-methods]
+---*/
+
+assert.sameValue(
+  Object.isExtensible(Set.prototype.union),
+  true,
+  "Built-in objects must be extensible."
+);
+
+assert.sameValue(
+  Object.prototype.toString.call(Set.prototype.union),
+  "[object Function]",
+  "Object.prototype.toString"
+);
+
+assert.sameValue(
+  Object.getPrototypeOf(Set.prototype.union),
+  Function.prototype,
+  "prototype"
+);

test/built-ins/Set/prototype/union/called-with-object.js

@@ -0,0 +1,66 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-getsetrecord
+description: GetSetRecord throws if obj is not an object
+info: |
+    1. If obj is not an Object, throw a TypeError exception.
+features: [Set-methods]
+---*/
+
+let s1 = new Set([1]);
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(1);
+  },
+  "number"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union("");
+  },
+  "string"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(1n);
+  },
+  "bigint"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(false);
+  },
+  "boolean"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(undefined);
+  },
+  "undefined"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(null);
+  },
+  "null"
+);
+
+assert.throws(
+  TypeError,
+  function () {
+    s1.union(Symbol("test"));
+  },
+  "symbol"
+);

test/built-ins/Set/prototype/union/combines-Map.js

@@ -0,0 +1,19 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union combines with Map
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const m1 = new Map([
+  [2, "two"],
+  [3, "three"],
+]);
+const expected = [1, 2, 3];
+const combined = s1.union(m1);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/combines-empty-sets.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union can combine empty Sets
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([]);
+const s2 = new Set([1, 2]);
+let expected = [1, 2];
+let combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
+
+const s3 = new Set([1, 2]);
+const s4 = new Set([]);
+expected = [1, 2];
+combined = s3.union(s4);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
+
+const s5 = new Set([]);
+const s6 = new Set([]);
+expected = [];
+combined = s5.union(s6);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/combines-itself.js

@@ -0,0 +1,15 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union is successful when called on itself
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const expected = [1, 2];
+const combined = s1.union(s1);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/combines-same-sets.js

@@ -0,0 +1,16 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union can combine Sets that have the same content
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = new Set([1, 2]);
+const expected = [1, 2];
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/combines-sets.js

@@ -0,0 +1,16 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union combines Sets
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const s1 = new Set([1, 2]);
+const s2 = new Set([2, 3]);
+const expected = [1, 2, 3];
+const combined = s1.union(s2);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");

test/built-ins/Set/prototype/union/converts-negative-zero.js

@@ -0,0 +1,35 @@
+// Copyright (C) 2023 Anthony Frehner. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-set.prototype.union
+description: Set.prototype.union converts -0𝔽 to +0𝔽
+info: |
+    7.b.ii. If nextValue is -0𝔽, set nextValue to +0𝔽.
+features: [Set-methods]
+includes: [compareArray.js]
+---*/
+
+const setlikeWithMinusZero = {
+  size: 1,
+  has: function () {
+    throw new Test262Error("Set.prototype.union should not invoke .has on its argument");
+  },
+  keys: function () {
+    // we use an array here because the Set constructor would normalize away -0
+    return [-0].values();
+  },
+};
+
+const s1 = new Set([1]);
+let expected = [1, +0];
+let combined = s1.union(setlikeWithMinusZero);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");
+
+const s2 = new Set([+0]);
+expected = [+0];
+combined = s2.union(setlikeWithMinusZero);
+
+assert.compareArray([...combined], expected);
+assert.sameValue(combined instanceof Set, true, "The returned object is a Set");