test/mjsunit/array-elements-from-array-prototype-chain.js

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////////////////////////////////////////////////////////////////////////
// Tests below verify that elements set on Array.prototype's proto propagate
// for various Array.prototype functions (like unshift, shift, etc.)
// If add any new tests here, consider adding them to all other files:
//   array-elements-from-array-prototype.js
//   array-elements-from-array-prototype-chain.js
//   array-elements-from-object-prototype.js
// those ideally should be identical modulo host of elements and
// the way elements introduced.
//
// Note: they are put into a separate file as we need maximally clean
// VM setup---some optimizations might be already turned off in
// 'dirty' VM.
////////////////////////////////////////////////////////////////////////

var at3 = '@3'
var at7 = '@7'

Array.prototype.__proto__ = {3: at3};
Array.prototype.__proto__.__proto__ = {7: at7};

var a = new Array(13)

assertEquals(at3, a[3])
assertFalse(a.hasOwnProperty(3))

assertEquals(at7, a[7])
assertFalse(a.hasOwnProperty(7))

assertEquals(undefined, a.shift(), 'hole should be returned as undefined')
// Side-effects: Array.prototype[3] percolates into a[2] and Array.prototype[7[
// into a[6], still visible at the corresponding indices.

assertEquals(at3, a[2])
assertTrue(a.hasOwnProperty(2))
assertEquals(at3, a[3])
assertFalse(a.hasOwnProperty(3))

assertEquals(at7, a[6])
assertTrue(a.hasOwnProperty(6))
assertEquals(at7, a[7])
assertFalse(a.hasOwnProperty(7))

a.unshift('foo', 'bar')
// Side-effects: Array.prototype[3] now percolates into a[5] and Array.prototype[7]
// into a[9].

assertEquals(at3, a[3])
assertFalse(a.hasOwnProperty(3))
assertEquals(at3, a[4])
assertTrue(a.hasOwnProperty(4))
assertEquals(at3, a[5])
assertTrue(a.hasOwnProperty(5))

assertEquals(undefined, a[6])
assertFalse(a.hasOwnProperty(6))

assertEquals(at7, a[7])
assertFalse(a.hasOwnProperty(7))
assertEquals(at7, a[8])
assertTrue(a.hasOwnProperty(8))
assertEquals(at7, a[9])
assertTrue(a.hasOwnProperty(9))

var sliced = a.slice(3, 10)
// Slice must keep intact a and reify holes at indices 0--2 and 4--6.

assertEquals(at3, a[3])
assertFalse(a.hasOwnProperty(3))
assertEquals(at3, a[4])
assertTrue(a.hasOwnProperty(4))
assertEquals(at3, a[5])
assertTrue(a.hasOwnProperty(5))

assertEquals(undefined, a[6])
assertFalse(a.hasOwnProperty(6))

assertEquals(at7, a[7])
assertFalse(a.hasOwnProperty(7))
assertEquals(at7, a[8])
assertTrue(a.hasOwnProperty(8))
assertEquals(at7, a[9])
assertTrue(a.hasOwnProperty(9))

assertEquals(at3, sliced[0])
assertTrue(sliced.hasOwnProperty(0))
assertEquals(at3, sliced[1])
assertTrue(sliced.hasOwnProperty(1))
assertEquals(at3, sliced[2])
assertTrue(sliced.hasOwnProperty(2))

// Note: sliced[3] comes directly from Array.prototype[3]
assertEquals(at3, sliced[3]);
assertFalse(sliced.hasOwnProperty(3))

assertEquals(at7, sliced[4])
assertTrue(sliced.hasOwnProperty(4))
assertEquals(at7, sliced[5])
assertTrue(sliced.hasOwnProperty(5))
assertEquals(at7, sliced[6])
assertTrue(sliced.hasOwnProperty(6))


// Splice is too complicated the operation, start afresh.

// Shrking array.
var a0 = [0, 1, , , 4, 5, , , , 9]
var result = a0.splice(4, 1)
// Side-effects: everything before 4 is kept intact:

assertEquals(0, a0[0])
assertTrue(a0.hasOwnProperty(0))
assertEquals(1, a0[1])
assertTrue(a0.hasOwnProperty(1))
assertEquals(undefined, a0[2])
assertFalse(a0.hasOwnProperty(2))
assertEquals(at3, a0[3])
assertFalse(a0.hasOwnProperty(3))

// 4 and above shifted left by one reifying at7 into a0[6] and keeping
// a hole at a0[7]

assertEquals(5, a0[4])
assertTrue(a0.hasOwnProperty(4))
assertEquals(undefined, a0[5])
assertFalse(a0.hasOwnProperty(5))
assertEquals(at7, a0[6])
assertTrue(a0.hasOwnProperty(6))
assertEquals(at7, a0[7])
assertFalse(a0.hasOwnProperty(7))
assertEquals(9, a0[8])
assertTrue(a0.hasOwnProperty(8))

// Growing array.
var a1 = [0, 1, , , 4, 5, , , , 9]
var result = a1.splice(4, 0, undefined)
// Side-effects: everything before 4 is kept intact:

assertEquals(0, a1[0])
assertTrue(a1.hasOwnProperty(0))
assertEquals(1, a1[1])
assertTrue(a1.hasOwnProperty(1))
assertEquals(undefined, a1[2])
assertFalse(a1.hasOwnProperty(2))
assertEquals(at3, a1[3])
assertFalse(a1.hasOwnProperty(3))

// Now owned undefined resides at 4 and rest is shifted right by one
// reifying at7 into a0[8] and keeping a hole at a0[7].

assertEquals(undefined, a1[4])
assertTrue(a1.hasOwnProperty(4))
assertEquals(4, a1[5])
assertTrue(a1.hasOwnProperty(5))
assertEquals(5, a1[6])
assertTrue(a1.hasOwnProperty(6))
assertEquals(at7, a1[7])
assertFalse(a1.hasOwnProperty(7))
assertEquals(at7, a1[8])
assertTrue(a1.hasOwnProperty(8))
assertEquals(undefined, a1[9])
assertFalse(a1.hasOwnProperty(9))
assertEquals(9, a1[10])
assertTrue(a1.hasOwnProperty(10))