arrow-rest-params.js

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

(function testRestIndex() {
  assertEquals(5, ((...args) => args.length)(1,2,3,4,5));
  assertEquals(4, ((a, ...args) => args.length)(1,2,3,4,5));
  assertEquals(3, ((a, b, ...args) => args.length)(1,2,3,4,5));
  assertEquals(2, ((a, b, c, ...args) => args.length)(1,2,3,4,5));
  assertEquals(1, ((a, b, c, d, ...args) => args.length)(1,2,3,4,5));
  assertEquals(0, ((a, b, c, d, e, ...args) => args.length)(1,2,3,4,5));
})();

// strictTest and sloppyTest should be called with descending natural
// numbers, as in:
//
//   strictTest(6,5,4,3,2,1)
//
var strictTest = (() => {
  "use strict";
  return (a, b, ...c) => {
    assertEquals(Array, c.constructor);
    assertTrue(Array.isArray(c));

    var expectedLength = (a === undefined) ? 0 : a - 2;
    assertEquals(expectedLength, c.length);

    for (var i = 2; i < a; ++i) {
      assertEquals(c[i - 2], a - i);
    }
  };
})();

var sloppyTest = (a, b, ...c) => {
  assertEquals(Array, c.constructor);
  assertTrue(Array.isArray(c));

  var expectedLength = (a === undefined) ? 0 : a - 2;
  assertEquals(expectedLength, c.length);

  for (var i = 2; i < a; ++i) {
    assertEquals(c[i - 2], a - i);
  }
}


var O = {
  strict: strictTest,
  sloppy: sloppyTest
};

(function testStrictRestParamArity() {
  assertEquals(2, strictTest.length);
  assertEquals(2, O.strict.length);
})();


(function testRestParamsStrictMode() {
  strictTest();
  strictTest(2, 1);
  strictTest(6, 5, 4, 3, 2, 1);
  strictTest(3, 2, 1);
  O.strict();
  O.strict(2, 1);
  O.strict(6, 5, 4, 3, 2, 1);
  O.strict(3, 2, 1);
})();


(function testRestParamsStrictModeApply() {
  strictTest.apply(null, []);
  strictTest.apply(null, [2, 1]);
  strictTest.apply(null, [6, 5, 4, 3, 2, 1]);
  strictTest.apply(null, [3, 2, 1]);
  O.strict.apply(O, []);
  O.strict.apply(O, [2, 1]);
  O.strict.apply(O, [6, 5, 4, 3, 2, 1]);
  O.strict.apply(O, [3, 2, 1]);
})();


(function testRestParamsStrictModeCall() {
  strictTest.call(null);
  strictTest.call(null, 2, 1);
  strictTest.call(null, 6, 5, 4, 3, 2, 1);
  strictTest.call(null, 3, 2, 1);
  O.strict.call(O);
  O.strict.call(O, 2, 1);
  O.strict.call(O, 6, 5, 4, 3, 2, 1);
  O.strict.call(O, 3, 2, 1);
})();


(function testsloppyRestParamArity() {
  assertEquals(2, sloppyTest.length);
  assertEquals(2, O.sloppy.length);
})();


(function testRestParamssloppyMode() {
  sloppyTest();
  sloppyTest(2, 1);
  sloppyTest(6, 5, 4, 3, 2, 1);
  sloppyTest(3, 2, 1);
  O.sloppy();
  O.sloppy(2, 1);
  O.sloppy(6, 5, 4, 3, 2, 1);
  O.sloppy(3, 2, 1);
})();


(function testRestParamssloppyModeApply() {
  sloppyTest.apply(null, []);
  sloppyTest.apply(null, [2, 1]);
  sloppyTest.apply(null, [6, 5, 4, 3, 2, 1]);
  sloppyTest.apply(null, [3, 2, 1]);
  O.sloppy.apply(O, []);
  O.sloppy.apply(O, [2, 1]);
  O.sloppy.apply(O, [6, 5, 4, 3, 2, 1]);
  O.sloppy.apply(O, [3, 2, 1]);
})();


(function testRestParamssloppyModeCall() {
  sloppyTest.call(null);
  sloppyTest.call(null, 2, 1);
  sloppyTest.call(null, 6, 5, 4, 3, 2, 1);
  sloppyTest.call(null, 3, 2, 1);
  O.sloppy.call(O);
  O.sloppy.call(O, 2, 1);
  O.sloppy.call(O, 6, 5, 4, 3, 2, 1);
  O.sloppy.call(O, 3, 2, 1);
})();


(function testUnmappedArguments() {
  // Normal functions make their arguments object unmapped, but arrow
  // functions don't have an arguments object anyway.  Check that the
  // right thing happens for arguments in arrow functions with rest
  // parameters.
  assertSame(arguments, ((...rest) => arguments)());
})();