Classes runtime

test/mjsunit/harmony/classes.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
+
+'use strict';
+
+(function TestBasics() {
+  var C = class C {}
+  assertEquals(typeof C, 'function');
+  assertEquals(C.__proto__, Function.prototype);
+  assertEquals(Object.prototype, Object.getPrototypeOf(C.prototype));
+  assertEquals(Function.prototype, Object.getPrototypeOf(C));
+  assertEquals('C', C.name);
+
+  class D {}
+  assertEquals(typeof D, 'function');
+  assertEquals(D.__proto__, Function.prototype);
+  assertEquals(Object.prototype, Object.getPrototypeOf(D.prototype));
+  assertEquals(Function.prototype, Object.getPrototypeOf(D));
+  assertEquals('D', D.name);
+
+  var E = class {}
+  assertEquals('', E.name);
+})();
+
+
+(function TestBasicsExtends() {
+  class C extends null {}
+  assertEquals(typeof C, 'function');
+  assertEquals(C.__proto__, Function.prototype);
+  assertEquals(null, Object.getPrototypeOf(C.prototype));
+
+  class D extends C {}
+  assertEquals(typeof D, 'function');
+  assertEquals(D.__proto__, C);
+  assertEquals(C.prototype, Object.getPrototypeOf(D.prototype));
+})();
+
+
+(function TestSideEffectInExtends() {
+  var calls = 0;
+  class C {}
+  class D extends (calls++, C) {}
+  assertEquals(1, calls);
+  assertEquals(typeof D, 'function');
+  assertEquals(D.__proto__, C);
+  assertEquals(C.prototype, Object.getPrototypeOf(D.prototype));
+})();
+
+
+(function TestInvalidExtends() {
+  assertThrows(function() {
+    class C extends 42 {}
+  }, TypeError);
+
+  assertThrows(function() {
+    // Function but its .prototype is not null or a function.
+    class C extends Math.abs {}
+  }, TypeError);
+
+  assertThrows(function() {
+    Math.abs.prototype = 42;
+    class C extends Math.abs {}
+  }, TypeError);
+  delete Math.abs.prototype;
+})();
+
+
+(function TestConstructorProperty() {
+  class C {}
+  assertEquals(C, C.prototype.constructor);
+  var descr = Object.getOwnPropertyDescriptor(C.prototype, 'constructor');
+  assertTrue(descr.configurable);
+  assertFalse(descr.enumerable);
+  assertTrue(descr.writable);
+})();
+
+
+(function TestPrototypeProperty() {
+  class C {}
+  var descr = Object.getOwnPropertyDescriptor(C, 'prototype');
+  assertFalse(descr.configurable);
+  assertFalse(descr.enumerable);
+  assertFalse(descr.writable);
+})();
+
+
+(function TestConstructor() {
+  var count = 0;
+  class C {
+    constructor() {
+      assertEquals(Object.getPrototypeOf(this), C.prototype);
+      count++;
+    }
+  }
+  assertEquals(C, C.prototype.constructor);
+  var descr = Object.getOwnPropertyDescriptor(C.prototype, 'constructor');
+  assertTrue(descr.configurable);
+  assertFalse(descr.enumerable);
+  assertTrue(descr.writable);
+
+  var c = new C();
+  assertEquals(1, count);
+  assertEquals(Object.getPrototypeOf(c), C.prototype);
+})();
+
+
+(function TestImplicitConstructor() {
+  class C {}
+  var c = new C();
+  assertEquals(Object.getPrototypeOf(c), C.prototype);
+})();
+
+
+(function TestConstructorStrict() {
+  class C {
+    constructor() {
+      assertThrows(function() {
+        nonExistingBinding = 42;
+      }, ReferenceError);
+    }
+  }
+  new C();
+})();
+
+
+(function TestSuperInConstructor() {
+  var calls = 0;
+  class B {}
+  B.prototype.x = 42;
+
+  class C extends B {
+    constructor() {
+      calls++;
+      assertEquals(42, super.x);
+    }
+  }
+
+  new C;
+  assertEquals(1, calls);
+})();
+
+
+/* TODO(arv): Implement
+(function TestNameBindingInConstructor() {
+  class C {
+    constructor() {
+      assertThrows(function() {
+        C = 42;
+      }, ReferenceError);
+    }
+  }
+  new C();
+})();
+*/