function shouldBe(actual, expected) { if (actual !== expected) throw new Error('bad value: ' + actual); } function shouldThrow(func, errorCondition) { var errorThrown = false; var error = null; try { func(); } catch (e) { errorThrown = true; error = e; } if (!errorThrown) throw new Error('not thrown'); if (!errorCondition(error)) throw new Error(`bad error: ${String(error)}`); } function strict(flag) { "use strict"; if (flag) throw arguments; return arguments.length; } noInline(strict); function sloppy(flag) { if (flag) throw arguments; return arguments.length; } noInline(sloppy); for (var i = 0; i < 1e6; ++i) { shouldBe(strict(false), 1); shouldBe(sloppy(false), 1); } function isArguments(arg) { shouldBe(String(arg), `[object Arguments]`); shouldBe(arg.length, 1); shouldBe(arg[0], true); return true; } shouldThrow(() => strict(true), isArguments); shouldThrow(() => sloppy(true), isArguments);