Add tests for Subclassing the built-in GeneratorFunction Objects

test/language/subclassing/GeneratorFunction/instance-length.js

@@ -0,0 +1,31 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 25.2.4.1
+description: >
+  Subclassed GeneratorFunction instances `length` property
+info: >
+  25.2.4.1 length
+
+  The value of the length property is an integer that indicates the typical
+  number of arguments expected by the GeneratorFunction. However, the language
+  permits the function to be invoked with some other number of arguments. The
+  behaviour of a GeneratorFunction when invoked on a number of arguments other
+  than the number specified by its length property depends on the function.
+
+  This property has the attributes { [[Writable]]: false, [[Enumerable]]: false,
+  [[Configurable]]: true }.
+includes: [propertyHelper.js]
+---*/
+
+var GeneratorFunction = Object.getPrototypeOf(function* () {}).constructor;
+
+class GFn extends GeneratorFunction {}
+
+var gfn = new GFn('a', 'b', 'return a + b');
+
+assert.sameValue(gfn.length, 2);
+
+verifyNotEnumerable(gfn, 'length');
+verifyNotWritable(gfn, 'length');
+verifyConfigurable(gfn, 'length');

test/language/subclassing/GeneratorFunction/instance-name.js

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+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 25.2.4.2
+description: Subclassed GeneratorFunction instances `name` property
+info: >
+  25.2.4.2 name
+
+  The specification for the name property of Function instances given in
+  19.2.4.2 also applies to GeneratorFunction instances.
+
+  19.2.4.2 name
+
+  The value of the name property is an String that is descriptive of the
+  function. The name has no semantic significance but is typically a variable or
+  property name that is used to refer to the function at its point of definition
+  in ECMAScript code. This property has the attributes { [[Writable]]: false,
+  [[Enumerable]]: false, [[Configurable]]: true }.
+
+  Anonymous functions objects that do not have a contextual name associated with
+  them by this specification do not have a name own property but inherit the
+  name property of %FunctionPrototype%.
+
+  19.2.1.1.1 RuntimeSemantics: CreateDynamicFunction(constructor, newTarget,
+  kind, args)
+
+  ...
+  29. Perform SetFunctionName(F, "anonymous").
+  ...
+includes: [propertyHelper.js]
+---*/
+
+var GeneratorFunction = Object.getPrototypeOf(function* () {}).constructor;
+
+class GFn extends GeneratorFunction {}
+
+var gfn = new GFn('a', 'b', 'return a + b');
+
+assert.sameValue(
+  gfn.name, 'anonymous',
+  'Dynamic Functions are called anonymous'
+);
+
+verifyNotEnumerable(gfn, 'name');
+verifyNotWritable(gfn, 'name');
+verifyConfigurable(gfn, 'name');

test/language/subclassing/GeneratorFunction/instance-prototype.js

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+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 25.2.4.3
+description: >
+  Subclassed GeneratorFunction instances `prototype` property
+info: >
+  25.2.4.3 prototype
+
+  Whenever a GeneratorFunction instance is created another ordinary object is
+  also created and is the initial value of the generator function’s prototype
+  property. The value of the prototype property is used to initialize the
+  [[Prototype]] internal slot of a newly created Generator object when the
+  generator function object is invoked using either [[Call]] or [[Construct]].
+
+  This property has the attributes { [[Writable]]: true, [[Enumerable]]: false,
+  [[Configurable]]: false }.
+includes: [propertyHelper.js]
+---*/
+
+var GeneratorFunction = Object.getPrototypeOf(function* () {}).constructor;
+
+class GFn extends GeneratorFunction {}
+
+var gfn = new GFn(';');
+
+assert.sameValue(
+  Object.keys(gfn.prototype).length, 0,
+  'prototype is a new ordinary object'
+);
+assert.sameValue(
+  gfn.prototype.hasOwnProperty('constructor'), false,
+  'prototype has no constructor reference'
+);
+
+verifyNotEnumerable(gfn, 'prototype');
+verifyWritable(gfn, 'prototype');
+verifyNotConfigurable(gfn, 'prototype');

test/language/subclassing/GeneratorFunction/regular-subclassing.js

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+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 25.2.1
+description: Subclassing GeneratorFunction
+info: >
+  25.2.1 The GeneratorFunction Constructor
+
+  ...
+
+  GeneratorFunction is designed to be subclassable. It may be used as the value
+  of an extends clause of a class definition. Subclass constructors that intend
+  to inherit the specified GeneratorFunction behaviour must include a super call
+  to the GeneratorFunction constructor to create and initialize subclass
+  instances with the internal slots necessary for built-in GeneratorFunction
+  behaviour.
+  ...
+---*/
+
+var GeneratorFunction = Object.getPrototypeOf(function* () {}).constructor;
+
+class Gfn extends GeneratorFunction {}
+
+var gfn = new Gfn('a', 'yield a; yield a * 2;');
+
+var iter = gfn(42);
+
+assert.sameValue(iter.next().value, 42);
+assert.sameValue(iter.next().value, 84);

test/language/subclassing/GeneratorFunction/super-must-be-called.js

@@ -0,0 +1,38 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 25.2.1
+description: >
+  super must be called to initialize GeneratorFunction internal slots
+info: >
+  25.2.1 The GeneratorFunction Constructor
+
+  ...
+
+  GeneratorFunction is designed to be subclassable. It may be used as the value
+  of an extends clause of a class definition. Subclass constructors that intend
+  to inherit the specified GeneratorFunction behaviour must include a super call
+  to the GeneratorFunction constructor to create and initialize subclass
+  instances with the internal slots necessary for built-in GeneratorFunction
+  behaviour.
+  ...
+---*/
+
+var GeneratorFunction = Object.getPrototypeOf(function* () {}).constructor;
+
+class GFn1 extends GeneratorFunction {
+  constructor() {}
+}
+
+assert.throws(ReferenceError, function() {
+  new GFn1();
+});
+
+class GFn2 extends GeneratorFunction {
+  constructor() {
+    super();
+  }
+}
+
+var fn = new GFn2();
+assert(fn instanceof GeneratorFunction);