ES6 Unscopables

test/mjsunit/harmony/unscopables.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.
+
+// Flags: --harmony-unscopables
+// Flags: --harmony-collections
+
+var global = this;
+var globalProto = Object.getPrototypeOf(global);
+
+// Number of objects being tested. There is an assert ensuring this is correct.
+var objectCount = 21;
+
+
+function runTest(f) {
+  function restore(object, oldProto) {
+    Object.setPrototypeOf(object, oldProto);
+    delete object[Symbol.unscopables];
+    delete object.x;
+    delete object.x_;
+    delete object.y;
+    delete object.z;
+  }
+
+  function getObject(i) {
+    var objects = [
+      {},
+      [],
+      function() {},
+      function() {
+        return arguments;
+      }(),
+      function() {
+        'use strict';
+        return arguments;
+      }(),
+      Object(1),
+      Object(true),
+      Object('bla'),
+      new Date,
+      new RegExp,
+      new Set,
+      new Map,
+      new WeakMap,
+      new WeakSet,
+      new ArrayBuffer(10),
+      new Int32Array(5),
+      Object,
+      Function,
+      Date,
+      RegExp,
+      global
+    ];
+
+    assertEquals(objectCount, objects.length);
+    return objects[i];
+  }
+
+  if (f.length === 1) {
+    for (var i = 0; i < objectCount; i++) {
+      var object = getObject(i);
+      var oldObjectProto = Object.getPrototypeOf(object);
+      f(object);
+      restore(object, oldObjectProto);
+    }
+  } else {
+    for (var i = 0; i < objectCount; i++) {
+      for (var j = 0; j < objectCount; j++) {
+        var object = getObject(i);
+        var proto = getObject(j);
+        if (object === proto) {
+          continue;
+        }
+        var oldObjectProto = Object.getPrototypeOf(object);
+        var oldProtoProto = Object.getPrototypeOf(proto);
+        f(object, proto);
+        restore(object, oldObjectProto);
+        restore(proto, oldProtoProto);
+      }
+    }
+  }
+}
+
+
+function TestBasics(object) {
+  var x = 1;
+  var y = 2;
+  var z = 3;
+  object.x = 4;
+  object.y = 5;
+
+  with (object) {
+    assertEquals(4, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
+
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
+
+  object[Symbol.unscopables] = {x: 0, y: true};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(2, y);
+    assertEquals(3, z);
+  }
+}
+runTest(TestBasics);
+
+
+function TestBasicsSet(object) {
+  var x = 1;
+  object.x = 2;
+
+  with (object) {
+    assertEquals(2, x);
+  }
+
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    assertEquals(1, x);
+    x = 3;
+    assertEquals(3, x);
+  }
+
+  assertEquals(3, x);
+  assertEquals(2, object.x);
+}
+runTest(TestBasicsSet);
+
+
+function TestOnProto(object, proto) {
+  var x = 1;
+  var y = 2;
+  var z = 3;
+  proto.x = 4;
+
+  Object.setPrototypeOf(object, proto);
+  object.y = 5;
+
+  with (object) {
+    assertEquals(4, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
+
+  proto[Symbol.unscopables] = {x: true};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
+
+  object[Symbol.unscopables] = {y: true};
+  with (object) {
+    assertEquals(1, x);
+    assertEquals(2, y);
+    assertEquals(3, z);
+  }
+
+  proto[Symbol.unscopables] = {y: true};
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    assertEquals(4, x);
+    assertEquals(5, y);
+    assertEquals(3, z);
+  }
+}
+runTest(TestOnProto);
+
+
+function TestNonObject(object) {
+  var x = 1;
+  var y = 2;
+  object.x = 3;
+  object.y = 4;
+
+  object[Symbol.unscopables] = 'xy';
+  with (object) {
+    assertEquals(3, x);
+    assertEquals(4, y);
+  }
+
+  object[Symbol.unscopables] = null;
+  with (object) {
+    assertEquals(3, x);
+    assertEquals(4, y);
+  }
+}
+runTest(TestNonObject);
+
+
+function TestChangeDuringWith(object) {
+  var x = 1;
+  var y = 2;
+  object.x = 3;
+  object.y = 4;
+
+  with (object) {
+    assertEquals(3, x);
+    assertEquals(4, y);
+    object[Symbol.unscopables] = {x: true};
+    assertEquals(1, x);
+    assertEquals(4, y);
+  }
+}
+runTest(TestChangeDuringWith);
+
+
+function TestChangeDuringWithWithPossibleOptimization(object) {
+  var x = 1;
+  object.x = 2;
+  with (object) {
+    for (var i = 0; i < 1000; i++) {
+      if (i === 500) object[Symbol.unscopables] = {x: true};
+      assertEquals(i < 500 ? 2: 1, x);
+    }
+  }
+}
+TestChangeDuringWithWithPossibleOptimization({});
+
+
+function TestChangeDuringWithWithPossibleOptimization2(object) {
+  var x = 1;
+  object.x = 2;
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    for (var i = 0; i < 1000; i++) {
+      if (i === 500) delete object[Symbol.unscopables];
+      assertEquals(i < 500 ? 1 : 2, x);
+    }
+  }
+}
+TestChangeDuringWithWithPossibleOptimization2({});
+
+
+function TestChangeDuringWithWithPossibleOptimization3(object) {
+  var x = 1;
+  object.x = 2;
+  object[Symbol.unscopables] = {};
+  with (object) {
+    for (var i = 0; i < 1000; i++) {
+      if (i === 500) object[Symbol.unscopables].x = true;
+      assertEquals(i < 500 ? 2 : 1, x);
+    }
+  }
+}
+TestChangeDuringWithWithPossibleOptimization3({});
+
+
+function TestChangeDuringWithWithPossibleOptimization4(object) {
+  var x = 1;
+  object.x = 2;
+  object[Symbol.unscopables] = {x: true};
+  with (object) {
+    for (var i = 0; i < 1000; i++) {
+      if (i === 500) delete object[Symbol.unscopables].x;
+      assertEquals(i < 500 ? 1 : 2, x);
+    }
+  }
+}
+TestChangeDuringWithWithPossibleOptimization4({});
+
+
+(function TestGlobal() {
+  global.values = 'global.values';
+  Array.prototype.values = 'Array.prototype.values';
+  Array.prototype[Symbol.unscopables] = {values: true};
+  Array.prototype.__proto__ = {values: 42};
+  var array = [];
+  with (array) {
+    assertEquals(42, values);
+  }
+})();
+
+
+function TestAccessorReceiver(object, proto) {
+  var x = 'local';
+
+  Object.defineProperty(proto, 'x', {
+    get: function() {
+      assertEquals(object, this);
+      return this.x_;
+    },
+    configurable: true
+  });
+  proto.x_ = 'proto';
+
+  Object.setPrototypeOf(object, proto);
+  proto.x_ = 'object';
+
+  with (object) {
+    assertEquals('object', x);
+  }
+}
+runTest(TestAccessorReceiver);
+
+
+function TestUnscopablesGetter(object) {
+  // This test gets really messy when object is the global since the assert
+  // functions are properties on the global object and the call count gets
+  // completely different.
+  if (object === global) return;
+
+  var x = 'local';
+  object.x = 'object';
+
+  var callCount = 0;
+  Object.defineProperty(object, Symbol.unscopables, {
+    get: function() {
+      callCount++;
+      return {};
+    },
+    configurable: true
+  });
+  with (object) {
+    assertEquals('object', x);
+  }
+  // Once for HasBinding and once for GetBindingValue
+  assertEquals(2, callCount);
+
+  callCount = 0;
+  Object.defineProperty(object, Symbol.unscopables, {
+    get: function() {
+      callCount++;
+      return {x: true};
+    },
+    configurable: true
+  });
+  with (object) {
+    assertEquals('local', x);
+  }
+  // Once for HasBinding
+  assertEquals(1, callCount);
+
+  callCount = 0;
+  Object.defineProperty(object, Symbol.unscopables, {
+    get: function() {
+      callCount++;
+      return callCount === 1 ? {} : {x: true};
+    },
+    configurable: true
+  });
+  with (object) {
+    assertEquals(void 0, x);
+  }
+  // Once for HasBinding, once for GetBindingValue.
+  assertEquals(2, callCount);
+
+  callCount = 0;
+  Object.defineProperty(object, Symbol.unscopables, {
+    get: function() {
+      callCount++;
+      return callCount === 1 ? {} : {x: true};
+    },
+    configurable: true
+  });
+  with (object) {
+    x = 1;
+  }
+  // Once for HasBinding
+  assertEquals(1, callCount);
+  assertEquals(1, object.x);
+  assertEquals('local', x);
+  with (object) {
+    x = 2;
+  }
+  // One more HasBinding.
+  assertEquals(2, callCount);
+  assertEquals(1, object.x);
+  assertEquals(2, x);
+}
+runTest(TestUnscopablesGetter);
+
+
+var global = this;
+(function TestUnscopablesGetter2() {
+  var x = 'local';
+
+  var protos = [{}, [], function() {}, global];
+  var objects = [{}, [], function() {}];
+
+  protos.forEach(function(proto) {
+    objects.forEach(function(object) {
+      Object.defineProperty(proto, 'x', {
+        get: function() {
+          assertEquals(object, this);
+          return 'proto';
+        },
+        configurable: true
+      });
+
+      object.__proto__ = proto;
+      Object.defineProperty(object, 'x', {
+        get: function() {
+          assertEquals(object, this);
+          return 'object';
+        },
+        configurable: true
+      });
+
+      with (object) {
+        assertEquals('object', x);
+      }
+
+      object[Symbol.unscopables] = {x: true};
+      with (object) {
+        assertEquals('proto', x);
+      }
+
+      delete proto[Symbol.unscopables];
+      delete object[Symbol.unscopables];
+    });
+  });
+})();
+
+
+function TestSetterOnBlacklisted(object, proto) {
+  Object.defineProperty(proto, 'x', {
+    set: function(x) {
+      assertUnreachable();
+    },
+    get: function() {
+      return 'proto';
+    },
+    configurable: true
+  });
+  Object.setPrototypeOf(object, proto);
+  Object.defineProperty(object, 'x', {
+    get: function() {
+      return this.x_;
+    },
+    set: function(x) {
+      this.x_ = x;
+    },
+    configurable: true
+  });
+  object.x_ = 1;
+
+  with (object) {
+    x = 2;
+    assertEquals(2, x);
+  }
+
+  assertEquals(2, object.x);
+
+  object[Symbol.unscopables] = {x: true};
+
+  with (object) {
+    x = 3;
+    assertEquals('proto', x);
+  }
+
+  assertEquals(3, object.x);
+}
+runTest(TestSetterOnBlacklisted);
+
+
+function TestObjectsAsUnscopables(object, unscopables) {
+  var x = 1;
+  object.x = 2;
+
+  with (object) {
+    assertEquals(2, x);
+    object[Symbol.unscopables] = unscopables;
+    assertEquals(2, x);
+  }
+}
+runTest(TestAccessorOnUnscopables);
+
+
+function TestAccessorOnUnscopables(object) {
+  var x = 1;
+  object.x = 2;
+
+  var unscopables = {
+    get x() {
+      assertUnreachable();
+    }
+  };
+
+  with (object) {
+    assertEquals(2, x);
+    object[Symbol.unscopables] = unscopables;
+    assertEquals(1, x);
+  }
+}
+runTest(TestAccessorOnUnscopables);
+
+
+function TestLengthUnscopables(object, proto) {
+  var length = 2;
+  with (object) {
+    assertEquals(1, length);
+    object[Symbol.unscopables] = {length: true};
+    assertEquals(0, length);  // From prototype
+    proto[Symbol.unscopables] = {length: true};
+    assertEquals(2, length);
+    delete proto[Symbol.unscopables];
+    assertEquals(0, length);  // From prototype
+  }
+}
+TestLengthUnscopables([1], Array.prototype);
+TestLengthUnscopables(function(x) {}, Function.prototype);
+TestLengthUnscopables(new String('x'), String.prototype);
+
+
+function TestFunctionNameUnscopables(object) {
+  var name = 'local';
+  with (object) {
+    assertEquals('f', name);
+    object[Symbol.unscopables] = {name: true};
+    assertEquals('Empty', name);  // From prototype
+    Object.getPrototypeOf(object)[Symbol.unscopables] = {name: true};
+    assertEquals('local', name);
+    delete Object.getPrototypeOf(object)[Symbol.unscopables];
+    assertEquals('Empty', name);  // From prototype
+  }
+}
+TestFunctionNameUnscopables(function f() {});
+
+
+function TestFunctionPrototypeUnscopables() {
+  var prototype = 'local';
+  var f = function() {};
+  var g = function() {};
+  Object.setPrototypeOf(f, g);
+  var fp = f.prototype;
+  var gp = g.prototype;
+  with (f) {
+    assertEquals(fp, prototype);
+    f[Symbol.unscopables] = {prototype: true};
+    assertEquals(gp, prototype);
+    g[Symbol.unscopables] = {prototype: true};
+    assertEquals('local', prototype);
+  }
+}
+TestFunctionPrototypeUnscopables(function() {});
+
+
+function TestFunctionArgumentsUnscopables() {
+  var func = function() {
+    var arguments = 'local';
+    var args = func.arguments;
+    with (func) {
+      assertEquals(args, arguments);
+      func[Symbol.unscopables] = {arguments: true};
+      assertEquals(null, arguments);  // From prototype
+      Function.prototype[Symbol.unscopables] = {arguments: true};
+      assertEquals('local', arguments);
+      delete Function.prototype[Symbol.unscopables];
+      assertEquals(null, arguments);  // From prototype
+    }
+  }
+  func(1);
+}
+TestFunctionArgumentsUnscopables();
+
+
+function TestArgumentsLengthUnscopables() {
+  var func = function() {
+    var length = 'local';
+    with (arguments) {
+      assertEquals(1, length);
+      arguments[Symbol.unscopables] = {length: true};
+      assertEquals('local', length);
+    }
+  }
+  func(1);
+}
+TestArgumentsLengthUnscopables();
+
+
+function TestFunctionCallerUnscopables() {
+  var func = function() {
+    var caller = 'local';
+    with (func) {
+      assertEquals(TestFunctionCallerUnscopables, caller);
+      func[Symbol.unscopables] = {caller: true};
+      assertEquals(null, caller);  // From prototype
+      Function.prototype[Symbol.unscopables] = {caller: true};
+      assertEquals('local', caller);
+      delete Function.prototype[Symbol.unscopables];
+      assertEquals(null, caller);  // From prototype
+    }
+  }
+  func(1);
+}
+TestFunctionCallerUnscopables();
+
+
+function TestGetUnscopablesGetterThrows() {
+  var object = {
+    get x() {
+      assertUnreachable();
+    }
+  };
+  function CustomError() {}
+  Object.defineProperty(object, Symbol.unscopables, {
+    get: function() {
+      throw new CustomError();
+    }
+  });
+  assertThrows(function() {
+    with (object) {
+      x;
+    }
+  }, CustomError);
+}
+TestGetUnscopablesGetterThrows();