Add initial tests for the "iterator-sequencing" proposal

features.txt

@@ -84,6 +84,10 @@ Atomics.pause
 # https://github.com/tc39/proposal-is-error
 Error.isError
 
+# Iterator Sequencing
+# https://github.com/tc39/proposal-iterator-sequencing
+iterator-sequencing
+
 ## Standard language features
 #
 # Language features that have been included in a published version of the

test/built-ins/Iterator/concat/arguments-checked-in-order.js

@@ -0,0 +1,42 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Arguments are validated in order.
+info: |
+  Iterator.concat ( ...items )
+
+  1. Let iterables be a new empty List.
+  2. For each element item of items, do
+    a. If item is not an Object, throw a TypeError exception.
+    b. Let method be ? GetMethod(item, %Symbol.iterator%).
+    ...
+features: [iterator-sequencing]
+---*/
+
+let getIterator = 0;
+
+let iterable1 = {
+  get [Symbol.iterator]() {
+    getIterator++;
+    return function() {
+      throw new Test262Error();
+    };
+  }
+};
+
+let iterable2 = {
+  get [Symbol.iterator]() {
+    throw new Test262Error();
+  }
+};
+
+assert.sameValue(getIterator, 0);
+
+assert.throws(TypeError, function() {
+  Iterator.concat(iterable1, null, iterable2);
+});
+
+assert.sameValue(getIterator, 1);

test/built-ins/Iterator/concat/fresh-iterator-result.js

@@ -0,0 +1,49 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Returns a fresh iterator result object
+info: |
+  Iterator.concat ( ...items )
+
+  ...
+  3. Let closure be a new Abstract Closure with no parameters that captures iterables and performs the following steps when called:
+    a. For each Record iterable of iterables, do
+      ...
+      v. Repeat, while innerAlive is true,
+        1. Let innerValue be ? IteratorStepValue(iteratorRecord).
+        2. If innerValue is done, then
+          ...
+        3. Else,
+          a. Let completion be Completion(Yield(innerValue)).
+    ...
+features: [iterator-sequencing]
+---*/
+
+let oldIterResult = {
+  done: false,
+  value: 123,
+};
+
+let testIterator = {
+  next() {
+    return oldIterResult;
+  }
+};
+
+let iterable = {
+  [Symbol.iterator]() {
+    return testIterator;
+  }
+};
+
+let iterator = Iterator.concat(iterable);
+
+let iterResult = iterator.next();
+
+assert.sameValue(iterResult.done, false);
+assert.sameValue(iterResult.value, 123);
+
+assert.notSameValue(iterResult, oldIterResult);

test/built-ins/Iterator/concat/get-iterator-method-only-once.js

@@ -0,0 +1,52 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Gets the iterator method from the input iterables only once.
+info: |
+  Iterator.concat ( ...items )
+
+  1. Let iterables be a new empty List.
+  2. For each element item of items, do
+    a. If item is not an Object, throw a TypeError exception.
+    b. Let method be ? GetMethod(item, %Symbol.iterator%).
+    c. If method is undefined, throw a TypeError exception.
+    d. Append the Record { [[OpenMethod]]: method, [[Iterable]]: item } to iterables.
+  ...
+features: [iterator-sequencing]
+includes: [compareArray.js]
+---*/
+
+let iteratorGets = 0;
+let iteratorCalls = 0;
+let array = [1, 2, 3];
+
+class CountingIterable {
+  get [Symbol.iterator]() {
+    ++iteratorGets;
+
+    return function () {
+      ++iteratorCalls;
+      return array[Symbol.iterator]();
+    };
+  }
+}
+
+let iterable = new CountingIterable();
+
+assert.sameValue(iteratorGets, 0);
+assert.sameValue(iteratorCalls, 0);
+
+let iter = Iterator.concat(iterable);
+
+assert.sameValue(iteratorGets, 1);
+assert.sameValue(iteratorCalls, 0);
+
+let result = [...iter];
+
+assert.sameValue(iteratorGets, 1);
+assert.sameValue(iteratorCalls, 1);
+
+assert.compareArray(result, array);

test/built-ins/Iterator/concat/get-iterator-method-throws.js

@@ -0,0 +1,27 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Error thrown when retrieving the iterator method.
+info: |
+  Iterator.concat ( ...items )
+
+  1. Let iterables be a new empty List.
+  2. For each element item of items, do
+    a. If item is not an Object, throw a TypeError exception.
+    b. Let method be ? GetMethod(item, %Symbol.iterator%).
+    ...
+features: [iterator-sequencing]
+---*/
+
+var iterable = {
+  get [Symbol.iterator]() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  Iterator.concat(iterable);
+});

test/built-ins/Iterator/concat/inner-iterator-created-in-order.js

@@ -0,0 +1,52 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Inner iterators created in order
+info: |
+  Iterator.concat ( ...items )
+
+  ...
+  3. Let closure be a new Abstract Closure with no parameters that captures iterables and performs the following steps when called:
+    a. For each Record iterable of iterables, do
+      i. Let iter be ? Call(iterable.[[OpenMethod]], iterable.[[Iterable]]).
+      ...
+      v. Repeat, while innerAlive is true,
+        ...
+features: [iterator-sequencing]
+includes: [compareArray.js]
+---*/
+
+let calledIterator = [];
+
+let iterable1 = {
+  [Symbol.iterator]() {
+    calledIterator.push("iterable1");
+    return [1][Symbol.iterator]();
+  }
+};
+
+let iterable2 = {
+  [Symbol.iterator]() {
+    calledIterator.push("iterable2");
+    return [2][Symbol.iterator]();
+  }
+};
+
+let iterator = Iterator.concat(iterable1, iterable2);
+
+assert.compareArray(calledIterator, []);
+
+let iterResult = iterator.next();
+assert.sameValue(iterResult.done, false);
+assert.sameValue(iterResult.value, 1);
+
+assert.compareArray(calledIterator, ["iterable1"]);
+
+iterResult = iterator.next();
+assert.sameValue(iterResult.done, false);
+assert.sameValue(iterResult.value, 2);
+
+assert.compareArray(calledIterator, ["iterable1", "iterable2"]);

test/built-ins/Iterator/concat/is-function.js

@@ -0,0 +1,15 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Iterator.concat is a built-in function
+features: [iterator-sequencing]
+---*/
+
+assert.sameValue(
+  typeof Iterator.concat,
+  "function",
+  "The value of `typeof Iterator.concat` is 'function'"
+);

test/built-ins/Iterator/concat/length.js

@@ -0,0 +1,23 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Iterator.concat has a "length" property whose value is 0.
+info: |
+  ECMAScript Standard Built-in Objects
+
+  Unless otherwise specified, the length property of a built-in
+  Function object has the attributes { [[Writable]]: false, [[Enumerable]]:
+  false, [[Configurable]]: true }.
+features: [iterator-sequencing]
+includes: [propertyHelper.js]
+---*/
+
+verifyProperty(Iterator.concat, "length", {
+  value: 0,
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});

test/built-ins/Iterator/concat/many-arguments.js

@@ -0,0 +1,45 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  Iterator.concat when called with many arguments.
+info: |
+  Iterator.concat ( ...items )
+
+  1. Let iterables be a new empty List.
+  2. For each element item of items, do
+    ...
+  3. Let closure be a new Abstract Closure with no parameters that captures iterables and performs the following steps when called:
+    a. For each Record iterable of iterables, do
+      ...
+    b. Return ReturnCompletion(undefined).
+  ...
+  6. Return gen.
+features: [iterator-sequencing]
+---*/
+
+let iterables = [
+  [/* empty */],
+  [1],
+  [2, 3],
+  [4, 5, 6],
+  [7, 8, 9, 10],
+];
+
+let iterator = Iterator.concat(...iterables);
+
+let array = [].concat(...iterables);
+
+for (let i = 0; i < array.length; i++) {
+  let iterResult = iterator.next();
+
+  assert.sameValue(iterResult.done, false);
+  assert.sameValue(iterResult.value, array[i]);
+}
+
+let iterResult = iterator.next();
+
+assert.sameValue(iterResult.done, true);
+assert.sameValue(iterResult.value, undefined);

test/built-ins/Iterator/concat/name.js

@@ -0,0 +1,30 @@
+// Copyright (C) 2024 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-iterator.concat
+description: >
+  The "name" property of Iterator.concat
+info: |
+  17 ECMAScript Standard Built-in Objects
+
+  Every built-in Function object, including constructors, that is not
+  identified as an anonymous function has a name property whose value is a
+  String. Unless otherwise specified, this value is the name that is given to
+  the function in this specification.
+
+  ...
+
+  Unless otherwise specified, the name property of a built-in Function
+  object, if it exists, has the attributes { [[Writable]]: false,
+  [[Enumerable]]: false, [[Configurable]]: true }.
+features: [iterator-sequencing]
+includes: [propertyHelper.js]
+---*/
+
+verifyProperty(Iterator.concat, "name", {
+  value: "concat",
+  writable: false,
+  enumerable: false,
+  configurable: true,
+});