Implement Proxy object [[getPrototypeOf]] internal method (#3623)

The algorithm is based on ECMA-262 v6, 9.5.1

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

tests/jerry/es2015/proxy_get_prototoype_of.js

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// TODO: Update these tests when the internal routine has been implemented
+// Copyright 2015 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.
 
 var target = {};
 var handler = { getPrototypeOf (target) {
@@ -26,7 +28,7 @@ try {
   Object.getPrototypeOf(proxy);
   assert(false);
 } catch (e) {
-  assert(e instanceof TypeError);
+  assert(e === 42);
 }
 
 try {
@@ -34,7 +36,7 @@ try {
   Object.prototype.isPrototypeOf(proxy);
   assert(false);
 } catch (e) {
-  assert(e instanceof TypeError);
+  assert(e === 42);
 }
 
 (function () {
@@ -49,7 +51,7 @@ try {
     g instanceof f;
     assert(false);
   } catch (e) {
-    assert(e instanceof TypeError);
+    assert(e === 42);
   }
 
   // ecma_op_implicit_class_constructor_has_instance [[GetPrototypeOf]]
@@ -57,7 +59,7 @@ try {
     g instanceof e;
     assert(false);
   } catch (e) {
-    assert(e instanceof TypeError);
+    assert(e === 42);
   }
 })();
 
@@ -68,3 +70,99 @@ try {
 } catch (e) {
   assert(e instanceof TypeError);
 }
+
+// test basic functionality
+var target = {};
+var handler = {
+  getPrototypeOf(target) {
+    return Array.prototype;
+  }
+}
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Array.prototype);
+assert(Reflect.getPrototypeOf(proxy) === Array.prototype);
+assert(Array.prototype.isPrototypeOf(proxy));
+assert(proxy instanceof Array);
+
+var obj = Object.preventExtensions({});
+assert(Object.getPrototypeOf(obj) === Object.prototype);
+
+var handler = {
+  getPrototypeOf(target) {
+    return Object.prototype;
+  }
+}
+var proxy = new Proxy(target, handler);
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with no trap
+var target = {};
+var handler = {};
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with "undefined" trap
+var target = {};
+var handler = { getPrototypeOf: null };
+var proxy = new Proxy(target, handler);
+
+assert(Object.getPrototypeOf(proxy) === Object.prototype);
+
+// test with invalid trap
+var target = {};
+var handler = { getPrototypeOf: 42 };
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy)
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+// test when target is proxy
+var target = {};
+var handler = {};
+var proxy = new Proxy(target, handler);
+
+var target_prototype = {};
+handler.getPrototypeOf = function() {
+  return target_prototype ;
+}
+
+var proxy2 = new Proxy(proxy, handler);
+assert(Object.getPrototypeOf(proxy2) === target_prototype);
+
+// test when invariants gets violated
+var target = {};
+var handler = {
+  getPrototypeOf(target) {
+    return 'foo';
+  }
+}
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}
+
+var target = Object.preventExtensions({});
+var handler = {
+  getPrototypeOf(target) {
+    return {};
+  }
+}
+
+var proxy = new Proxy(target, handler);
+
+try {
+  Object.getPrototypeOf(proxy);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}