function assert(b, ...m) { if (!b) throw new Error("Bad: ", ...m) } noInline(assert); class Foo extends Array { constructor(...args) { super(...args); } }; function shallowEq(a, b) { assert(a.length === b.length, a, b); for (let i = 0; i < a.length; i++) assert(a[i] === b[i], a, b); } noInline(shallowEq); let tests = [ [[1,2,3,4,5], [1,2,3,4,5], 0, 5], [[1,2,3,4,5], [1,2,3,4,5], 0], [[1,2,3,4,5], [4], -2, -1], [[1,2,3,4,5], [5], -1], [[1,2,3,4,5], [5], -1, 5], [[1,2,3,4,5], [], -10, -20], [[1,2,3,4,5], [], -20, -10], [[1,2,3,4,5], [], 6, 4], [[1,2,3,4,5], [], 3, 2], [[1,2,3,4,5], [4,5], 3, 10], [[1,2,3,4,5], [3,4,5], 2, 10], [[1,2,3,4,5], [1,2,3,4,5], -10, 10], [[1,2,3,4,5], [1,2,3,4,5], -5, 10], [[1,2,3,4,5], [2,3,4,5], -4, 10], ]; function runTest1(a, b) { let result = a.slice(b); assert(a instanceof Foo === result instanceof Foo); return result; } noInline(runTest1); function runTest2(a, b, c) { let result = a.slice(b, c); assert(a instanceof Foo === result instanceof Foo); return result; } noInline(runTest2); function addRandomProperties(input) { for (let i = 0; i < 4; i++) { input["prop" + i + ((Math.random() * 100000) | 0)] = i; } } noInline(addRandomProperties); function runTests() { for (let i = 0; i < 10000; i++) { for (let [input, output, ...args] of tests) { addRandomProperties(input); assert(args.length === 1 || args.length === 2); if (args.length === 1) shallowEq(runTest1(input, args[0]), output); else shallowEq(runTest2(input, args[0], args[1]), output); } } } runTests(); tests.push([new Foo(1,2,3,4,5), [1,2,3,4,5], -10, 10]); tests.push([new Foo(1,2,3,4,5), [1,2,3,4,5], -5, 10]); tests.push([new Foo(1,2,3,4,5), [2,3,4,5], -4, 10]); tests.push([new Foo(1,2,3,4,5), [2,3,4,5], -4]); runTests();