ES6 Unscopables

test/mjsunit/harmony/proxies-with-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-proxies
+
+
+// TODO(arv): Once proxies can intercept symbols, add more tests.
+
+
+function TestBasics() {
+  var log = [];
+
+  var proxy = Proxy.create({
+    getPropertyDescriptor: function(key) {
+      log.push(key);
+      if (key === 'x') {
+        return {
+          value: 1,
+          configurable: true
+        };
+      }
+      return undefined;
+    }
+  });
+
+  var x = 'local';
+
+  with (proxy) {
+    assertEquals(1, x);
+  }
+
+  // One 'x' for HasBinding and one for GetBindingValue
+  assertEquals(['assertEquals', 'x', 'x'], log);
+}
+TestBasics();
+
+
+function TestInconsistent() {
+  var log = [];
+  var calls = 0;
+
+  var proxy = Proxy.create({
+    getPropertyDescriptor: function(key) {
+      log.push(key);
+      if (key === 'x' && calls < 1) {
+        calls++;
+        return {
+          value: 1,
+          configurable: true
+        };
+      }
+      return undefined;
+    }
+  });
+
+  var x = 'local';
+
+  with (proxy) {
+    assertEquals(void 0, x);
+  }
+
+  // One 'x' for HasBinding and one for GetBindingValue
+  assertEquals(['assertEquals', 'x', 'x'], log);
+}
+TestInconsistent();
+
+
+function TestUseProxyAsUnscopables() {
+  var x = 1;
+  var object = {
+    x: 2
+  };
+  var calls = 0;
+  var proxy = Proxy.create({
+    has: function(key) {
+      calls++;
+      assertEquals('x', key);
+      return calls === 2;
+    },
+    getPropertyDescriptor: function(key) {
+      assertUnreachable();
+    }
+  });
+
+  object[Symbol.unscopables] = proxy;
+
+  with (object) {
+    assertEquals(2, x);
+    assertEquals(1, x);
+  }
+
+  // HasBinding, HasBinding
+  assertEquals(2, calls);
+}
+TestUseProxyAsUnscopables();
+
+
+function TestThrowInHasUnscopables() {
+  var x = 1;
+  var object = {
+    x: 2
+  };
+
+  function CustomError() {}
+
+  var calls = 0;
+  var proxy = Proxy.create({
+    has: function(key) {
+      if (calls++ === 0) {
+        throw new CustomError();
+      }
+      assertUnreachable();
+    },
+    getPropertyDescriptor: function(key) {
+      assertUnreachable();
+    }
+  });
+
+  object[Symbol.unscopables] = proxy;
+
+  assertThrows(function() {
+    with (object) {
+      x;
+    }
+  }, CustomError);
+}
+TestThrowInHasUnscopables();
+
+
+var global = this;
+function TestGlobalShouldIgnoreUnscopables() {
+  global.x = 1;
+  var proxy = Proxy.create({
+    getPropertyDescriptor: function() {
+      assertUnreachable();
+    }
+  });
+  global[Symbol.unscopables] = proxy;
+
+  assertEquals(1, global.x);
+  assertEquals(1, x);
+
+  global.x = 2;
+  assertEquals(2, global.x);
+  assertEquals(2, x);
+
+  x = 3;
+  assertEquals(3, global.x);
+  assertEquals(3, x);
+}
+TestGlobalShouldIgnoreUnscopables();