Added missing 'shrink' test for Array.prototype.reduce

test/built-ins/Array/prototype/reduce/resizable-buffer-shrink-mid-iteration.js

@@ -0,0 +1,79 @@
+// Copyright 2023 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-%array%.prototype.reduce
+description: >
+  Array.p.reduce behaves correctly when the backing resizable buffer is shrunk
+  mid-iteration.
+includes: [compareArray.js, resizableArrayBufferUtils.js]
+features: [resizable-arraybuffer]
+---*/
+
+let values;
+let rab;
+let resizeAfter;
+let resizeTo;
+// Collects the view of the resizable array buffer rab into values, with an
+// iteration during which, after resizeAfter steps, rab is resized to length
+// resizeTo. To be called by a method of the view being collected.
+// Note that rab, values, resizeAfter, and resizeTo may need to be reset
+// before calling this.
+function ResizeMidIteration(acc, n) {
+  // Returns true by default.
+  return CollectValuesAndResize(n, values, rab, resizeAfter, resizeTo);
+}
+
+// Orig. array: [0, 2, 4, 6]
+//              [0, 2, 4, 6] << fixedLength
+//                    [4, 6] << fixedLengthWithOffset
+//              [0, 2, 4, 6, ...] << lengthTracking
+//                    [4, 6, ...] << lengthTrackingWithOffset
+
+for (let ctor of ctors) {
+  values = [];
+  rab = CreateRabForTest(ctor);
+  const fixedLength = new ctor(rab, 0, 4);
+  resizeAfter = 2;
+  resizeTo = 3 * ctor.BYTES_PER_ELEMENT;
+  Array.prototype.reduce.call(fixedLength, ResizeMidIteration, 'initial value');
+  assert.compareArray(values, [
+    0,
+    2
+  ]);
+}
+for (let ctor of ctors) {
+  values = [];
+  rab = CreateRabForTest(ctor);
+  const fixedLengthWithOffset = new ctor(rab, 2 * ctor.BYTES_PER_ELEMENT, 2);
+  resizeAfter = 1;
+  resizeTo = 3 * ctor.BYTES_PER_ELEMENT;
+  Array.prototype.reduce.call(fixedLengthWithOffset, ResizeMidIteration, 'initial value');
+  assert.compareArray(values, [
+    4
+  ]);
+}
+for (let ctor of ctors) {
+  values = [];
+  rab = CreateRabForTest(ctor);
+  const lengthTracking = new ctor(rab, 0);
+  resizeAfter = 2;
+  resizeTo = 3 * ctor.BYTES_PER_ELEMENT;
+  Array.prototype.reduce.call(lengthTracking, ResizeMidIteration, 'initial value');
+  assert.compareArray(values, [
+    0,
+    2,
+    4
+  ]);
+}
+for (let ctor of ctors) {
+  values = [];
+  rab = CreateRabForTest(ctor);
+  const lengthTrackingWithOffset = new ctor(rab, 2 * ctor.BYTES_PER_ELEMENT);
+  resizeAfter = 1;
+  resizeTo = 3 * ctor.BYTES_PER_ELEMENT;
+  Array.prototype.reduce.call(lengthTrackingWithOffset, ResizeMidIteration, 'initial value');
+  assert.compareArray(values, [
+    4
+  ]);
+}