From a5d8e8e997872a76688884cf2199ff2bd2904274 Mon Sep 17 00:00:00 2001 From: rwaldron Date: Mon, 6 Dec 2021 09:43:17 -0500 Subject: [PATCH] test: Add more Array.from tests for array-like. Closes gh-3336 --- ...e-has-length-but-no-indexes-with-values.js | 39 +++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 test/built-ins/Array/from/array-like-has-length-but-no-indexes-with-values.js diff --git a/test/built-ins/Array/from/array-like-has-length-but-no-indexes-with-values.js b/test/built-ins/Array/from/array-like-has-length-but-no-indexes-with-values.js new file mode 100644 index 0000000000..46b403bdfb --- /dev/null +++ b/test/built-ins/Array/from/array-like-has-length-but-no-indexes-with-values.js @@ -0,0 +1,39 @@ +// Copyright (c) 2021 Rick Waldron. All rights reserved. +// This code is governed by the license found in the LICENSE file. + +/*--- +esid: sec-array.from +description: > + Creates an array with length that is equal to the value of the + length property of the given array-like, regardless of + the presence of corresponding indices and values. +info: | + Array.from ( items [ , mapfn [ , thisArg ] ] ) + + 7. Let arrayLike be ! ToObject(items). + 8. Let len be ? LengthOfArrayLike(arrayLike). + 9. If IsConstructor(C) is true, then + a. Let A be ? Construct(C, « 𝔽(len) »). + 10. Else, + a. Let A be ? ArrayCreate(len). + +includes: [compareArray.js] +---*/ + +const length = 5; + +const newlyCreatedArray = Array.from({ length }); +assert.sameValue( + newlyCreatedArray.length, + length, + "The newly created array's length is equal to the value of the length property for the provided array like object" +); +assert.compareArray(newlyCreatedArray, [undefined, undefined, undefined, undefined, undefined]); + +const newlyCreatedAndMappedArray = Array.from({ length }).map(x => 1); +assert.sameValue( + newlyCreatedAndMappedArray.length, + length, + "The newly created and mapped array's length is equal to the value of the length property for the provided array like object" +); +assert.compareArray(newlyCreatedAndMappedArray, [1, 1, 1, 1, 1]);