v8/test/mjsunit/es6/symbols.js

// Copyright 2013 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
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//
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// Flags: --expose-gc --allow-natives-syntax

var symbols = []


// Returns true if the string is a valid
// serialization of Symbols added to the 'symbols'
// array. Adjust if you extend 'symbols' with other
// values.
function isValidSymbolString(s) {
  return ["Symbol(66)", "Symbol()"].indexOf(s) >= 0;
}


// Test different forms of constructor calls.
function TestNew() {
  function indirectSymbol() { return Symbol() }
  function indirect() { return indirectSymbol() }
  for (var i = 0; i < 2; ++i) {
    for (var j = 0; j < 5; ++j) {
      symbols.push(Symbol())
      symbols.push(Symbol(undefined))
      symbols.push(Symbol("66"))
      symbols.push(Symbol(66))
      symbols.push(Symbol().valueOf())
      symbols.push(indirect())
    }
    %OptimizeFunctionOnNextCall(indirect)
    indirect()  // Call once before GC throws away type feedback.
    gc()        // Promote existing symbols and then allocate some more.
  }
  assertThrows(function () { Symbol(Symbol()) }, TypeError)
  assertThrows(function () { new Symbol(66) }, TypeError)
}
TestNew()


function TestType() {
  for (var i in symbols) {
    assertEquals("symbol", typeof symbols[i])
    assertTrue(typeof symbols[i] === "symbol")
    assertFalse(%SymbolIsPrivate(symbols[i]))
    assertEquals(null, %_ClassOf(symbols[i]))
    assertEquals("Symbol", %_ClassOf(Object(symbols[i])))
  }
}
TestType()


function TestPrototype() {
  assertSame(Object.prototype, Symbol.prototype.__proto__)
  assertSame(Symbol.prototype, Symbol().__proto__)
  assertSame(Symbol.prototype, Object(Symbol()).__proto__)
  for (var i in symbols) {
    assertSame(Symbol.prototype, symbols[i].__proto__)
  }
}
TestPrototype()


function TestConstructor() {
  assertSame(Function.prototype, Symbol.__proto__)
  assertFalse(Object === Symbol.prototype.constructor)
  assertFalse(Symbol === Object.prototype.constructor)
  assertSame(Symbol, Symbol.prototype.constructor)
  assertSame(Symbol, Symbol().__proto__.constructor)
  assertSame(Symbol, Object(Symbol()).__proto__.constructor)
  for (var i in symbols) {
    assertSame(Symbol, symbols[i].__proto__.constructor)
  }
}
TestConstructor()


function TestValueOf() {
  for (var i in symbols) {
    assertTrue(symbols[i] === Object(symbols[i]).valueOf())
    assertTrue(symbols[i] === symbols[i].valueOf())
    assertTrue(Symbol.prototype.valueOf.call(Object(symbols[i])) === symbols[i])
    assertTrue(Symbol.prototype.valueOf.call(symbols[i]) === symbols[i])
  }
}
TestValueOf()


function TestToString() {
  for (var i in symbols) {
    assertThrows(function() { String(symbols[i]) }, TypeError)
    assertThrows(function() { symbols[i] + "" }, TypeError)
    assertThrows(function() { String(Object(symbols[i])) }, TypeError)
    assertTrue(isValidSymbolString(symbols[i].toString()))
    assertTrue(isValidSymbolString(Object(symbols[i]).toString()))
    assertTrue(
      isValidSymbolString(Symbol.prototype.toString.call(symbols[i])))
    assertEquals(
      "[object Symbol]", Object.prototype.toString.call(symbols[i]))
  }
}
TestToString()


function TestToBoolean() {
  for (var i in symbols) {
    assertTrue(Boolean(Object(symbols[i])))
    assertFalse(!Object(symbols[i]))
    assertTrue(Boolean(symbols[i]).valueOf())
    assertFalse(!symbols[i])
    assertTrue(!!symbols[i])
    assertTrue(symbols[i] && true)
    assertFalse(!symbols[i] && false)
    assertTrue(!symbols[i] || true)
    assertEquals(1, symbols[i] ? 1 : 2)
    assertEquals(2, !symbols[i] ? 1 : 2)
    if (!symbols[i]) assertUnreachable();
    if (symbols[i]) {} else assertUnreachable();
  }
}
TestToBoolean()


function TestToNumber() {
  for (var i in symbols) {
    assertThrows(function() { Number(Object(symbols[i])) }, TypeError)
    assertThrows(function() { +Object(symbols[i]) }, TypeError)
    assertSame(NaN, Number(symbols[i]).valueOf())
    assertSame(NaN, symbols[i] + 0)
  }
}
TestToNumber()


function TestEquality() {
  // Every symbol should equal itself, and non-strictly equal its wrapper.
  for (var i in symbols) {
    assertSame(symbols[i], symbols[i])
    assertEquals(symbols[i], symbols[i])
    assertTrue(Object.is(symbols[i], symbols[i]))
    assertTrue(symbols[i] === symbols[i])
    assertTrue(symbols[i] == symbols[i])
    assertFalse(symbols[i] === Object(symbols[i]))
    assertFalse(Object(symbols[i]) === symbols[i])
    assertFalse(symbols[i] == Object(symbols[i]))
    assertFalse(Object(symbols[i]) == symbols[i])
    assertTrue(symbols[i] === symbols[i].valueOf())
    assertTrue(symbols[i].valueOf() === symbols[i])
    assertTrue(symbols[i] == symbols[i].valueOf())
    assertTrue(symbols[i].valueOf() == symbols[i])
    assertFalse(Object(symbols[i]) === Object(symbols[i]))
    assertEquals(Object(symbols[i]).valueOf(), Object(symbols[i]).valueOf())
  }

  // All symbols should be distinct.
  for (var i = 0; i < symbols.length; ++i) {
    for (var j = i + 1; j < symbols.length; ++j) {
      assertFalse(Object.is(symbols[i], symbols[j]))
      assertFalse(symbols[i] === symbols[j])
      assertFalse(symbols[i] == symbols[j])
    }
  }

  // Symbols should not be equal to any other value (and the test terminates).
  var values = [347, 1.275, NaN, "string", null, undefined, {}, function() {}]
  for (var i in symbols) {
    for (var j in values) {
      assertFalse(symbols[i] === values[j])
      assertFalse(values[j] === symbols[i])
      assertFalse(symbols[i] == values[j])
      assertFalse(values[j] == symbols[i])
    }
  }
}
TestEquality()


function TestGet() {
  for (var i in symbols) {
    assertTrue(isValidSymbolString(symbols[i].toString()))
    assertEquals(symbols[i], symbols[i].valueOf())
    assertEquals(undefined, symbols[i].a)
    assertEquals(undefined, symbols[i]["a" + "b"])
    assertEquals(undefined, symbols[i]["" + "1"])
    assertEquals(undefined, symbols[i][62])
  }
}
TestGet()


function TestSet() {
  for (var i in symbols) {
    symbols[i].toString = 0
    assertTrue(isValidSymbolString(symbols[i].toString()))
    symbols[i].valueOf = 0
    assertEquals(symbols[i], symbols[i].valueOf())
    symbols[i].a = 0
    assertEquals(undefined, symbols[i].a)
    symbols[i]["a" + "b"] = 0
    assertEquals(undefined, symbols[i]["a" + "b"])
    symbols[i][62] = 0
    assertEquals(undefined, symbols[i][62])
  }
}
TestSet()


// Test Symbol wrapping/boxing over non-builtins.
Symbol.prototype.getThisProto = function () {
  return Object.getPrototypeOf(this);
}
function TestCall() {
  for (var i in symbols) {
    assertTrue(symbols[i].getThisProto() === Symbol.prototype)
  }
}
TestCall()


function TestCollections() {
  var set = new Set
  var map = new Map
  var weakmap = new WeakMap
  for (var i in symbols) {
    set.add(symbols[i])
    map.set(symbols[i], i)
    weakmap.set(symbols[i], i)
  }
  assertEquals(symbols.length, set.size)
  assertEquals(symbols.length, map.size)
  for (var i in symbols) {
    assertTrue(set.has(symbols[i]))
    assertTrue(map.has(symbols[i]))
    assertTrue(weakmap.has(symbols[i]))
    assertEquals(i, map.get(symbols[i]))
    assertEquals(i, weakmap.get(symbols[i]))
  }
  for (var i in symbols) {
    assertTrue(set.delete(symbols[i]))
    assertTrue(map.delete(symbols[i]))
    assertTrue(weakmap.delete(symbols[i]))
  }
  assertEquals(0, set.size)
  assertEquals(0, map.size)
}
TestCollections()



function TestKeySet(obj) {
  assertTrue(%HasFastProperties(obj))
  // Set the even symbols via assignment.
  for (var i = 0; i < symbols.length; i += 2) {
    obj[symbols[i]] = i
    // Object should remain in fast mode until too many properties were added.
    assertTrue(%HasFastProperties(obj) || i >= 30)
  }
}


function TestKeyDefine(obj) {
  // Set the odd symbols via defineProperty (as non-enumerable).
  for (var i = 1; i < symbols.length; i += 2) {
    Object.defineProperty(obj, symbols[i], {value: i, configurable: true})
  }
}


function TestKeyGet(obj) {
  var obj2 = Object.create(obj)
  for (var i in symbols) {
    assertEquals(i|0, obj[symbols[i]])
    assertEquals(i|0, obj2[symbols[i]])
  }
}


function TestKeyHas(obj) {
  for (var i in symbols) {
    assertTrue(symbols[i] in obj)
    assertTrue(Object.hasOwnProperty.call(obj, symbols[i]))
  }
}


function TestKeyEnum(obj) {
  for (var name in obj) {
    assertEquals("string", typeof name)
  }
}


function TestKeyNames(obj) {
  assertEquals(0, Object.keys(obj).length)

  var names = Object.getOwnPropertyNames(obj)
  for (var i in names) {
    assertEquals("string", typeof names[i])
  }
}


function TestGetOwnPropertySymbols(obj) {
  var syms = Object.getOwnPropertySymbols(obj)
  assertEquals(syms.length, symbols.length)
  for (var i in syms) {
    assertEquals("symbol", typeof syms[i])
  }
}


function TestKeyDescriptor(obj) {
  for (var i in symbols) {
    var desc = Object.getOwnPropertyDescriptor(obj, symbols[i])
    assertEquals(i|0, desc.value)
    assertTrue(desc.configurable)
    assertEquals(i % 2 == 0, desc.writable)
    assertEquals(i % 2 == 0, desc.enumerable)
    assertEquals(i % 2 == 0,
        Object.prototype.propertyIsEnumerable.call(obj, symbols[i]))
  }
}


function TestKeyDelete(obj) {
  for (var i in symbols) {
    delete obj[symbols[i]]
  }
  for (var i in symbols) {
    assertEquals(undefined, Object.getOwnPropertyDescriptor(obj, symbols[i]))
  }
}


var objs = [{}, [], Object.create(null), Object(1), new Map, function(){}]

for (var i in objs) {
  var obj = objs[i]
  TestKeySet(obj)
  TestKeyDefine(obj)
  TestKeyGet(obj)
  TestKeyHas(obj)
  TestKeyEnum(obj)
  TestKeyNames(obj)
  TestGetOwnPropertySymbols(obj)
  TestKeyDescriptor(obj)
  TestKeyDelete(obj)
}


function TestDefineProperties() {
  var properties = {}
  for (var i in symbols) {
    Object.defineProperty(
        properties, symbols[i], {value: {value: i}, enumerable: i % 2 === 0})
  }
  var o = Object.defineProperties({}, properties)
  for (var i in symbols) {
    assertEquals(i % 2 === 0, symbols[i] in o)
  }
}
TestDefineProperties()


function TestCreate() {
  var properties = {}
  for (var i in symbols) {
    Object.defineProperty(
      properties, symbols[i], {value: {value: i}, enumerable: i % 2 === 0})
  }
  var o = Object.create(Object.prototype, properties)
  for (var i in symbols) {
    assertEquals(i % 2 === 0, symbols[i] in o)
  }
}
TestCreate()


function TestCachedKeyAfterScavenge() {
  gc();
  // Keyed property lookup are cached.  Hereby we assume that the keys are
  // tenured, so that we only have to clear the cache between mark compacts,
  // but not between scavenges.  This must also apply for symbol keys.
  var key = Symbol("key");
  var a = {};
  a[key] = "abc";

  for (var i = 0; i < 100000; i++) {
    a[key] += "a";  // Allocations cause a scavenge.
  }
}
TestCachedKeyAfterScavenge();


function TestGetOwnPropertySymbolsWithProto() {
  // We need to be have fast properties to have insertion order for property
  // keys. The current limit is currently 30 properties.
  var syms = symbols.slice(0, 30);
  var proto = {}
  var object = Object.create(proto)
  for (var i = 0; i < syms.length; i++) {
    // Even on object, odd on proto.
    if (i % 2) {
      proto[syms[i]] = i
    } else {
      object[syms[i]] = i
    }
  }

  assertTrue(%HasFastProperties(object));

  var objectOwnSymbols = Object.getOwnPropertySymbols(object)
  assertEquals(objectOwnSymbols.length, syms.length / 2)

  for (var i = 0; i < objectOwnSymbols.length; i++) {
    assertEquals(objectOwnSymbols[i], syms[i * 2])
  }
}
TestGetOwnPropertySymbolsWithProto()


function TestWellKnown() {
  var symbols = [
    // TODO(rossberg): reactivate once implemented.
    // "hasInstance", "isConcatSpreadable", "isRegExp",
    "iterator", /* "toStringTag", */ "unscopables"
  ]

  for (var i in symbols) {
    var name = symbols[i]
    var desc = Object.getOwnPropertyDescriptor(Symbol, name)
    assertSame("symbol", typeof desc.value)
    assertSame("Symbol(Symbol." + name + ")", desc.value.toString())
    assertFalse(desc.writable)
    assertFalse(desc.configurable)
    assertFalse(desc.enumerable)

    assertFalse(Symbol.for("Symbol." + name) === desc.value)
    assertTrue(Symbol.keyFor(desc.value) === undefined)
  }
}
TestWellKnown()


function TestRegistry() {
  var symbol1 = Symbol.for("x1")
  var symbol2 = Symbol.for("x2")
  assertFalse(symbol1 === symbol2)

  assertSame(symbol1, Symbol.for("x1"))
  assertSame(symbol2, Symbol.for("x2"))
  assertSame("x1", Symbol.keyFor(symbol1))
  assertSame("x2", Symbol.keyFor(symbol2))

  assertSame(Symbol.for("1"), Symbol.for(1))
  assertThrows(function() { Symbol.keyFor("bla") }, TypeError)
  assertThrows(function() { Symbol.keyFor({}) }, TypeError)

  var realm = Realm.create()
  assertFalse(Symbol === Realm.eval(realm, "Symbol"))
  assertFalse(Symbol.for === Realm.eval(realm, "Symbol.for"))
  assertFalse(Symbol.keyFor === Realm.eval(realm, "Symbol.keyFor"))
  assertSame(Symbol.create, Realm.eval(realm, "Symbol.create"))
  assertSame(Symbol.iterator, Realm.eval(realm, "Symbol.iterator"))

  assertSame(symbol1, Realm.eval(realm, "Symbol.for")("x1"))
  assertSame(symbol1, Realm.eval(realm, "Symbol.for('x1')"))
  assertSame("x1", Realm.eval(realm, "Symbol.keyFor")(symbol1))
  Realm.shared = symbol1
  assertSame("x1", Realm.eval(realm, "Symbol.keyFor(Realm.shared)"))

  var symbol3 = Realm.eval(realm, "Symbol.for('x3')")
  assertFalse(symbol1 === symbol3)
  assertFalse(symbol2 === symbol3)
  assertSame(symbol3, Symbol.for("x3"))
  assertSame("x3", Symbol.keyFor(symbol3))
}
TestRegistry()