Add Dart API method Dart_SetPersistentHandle to enable setting the value of

runtime/vm/dart_api_impl_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/builtin.h"
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
@@ skipping 1879 matching lines @@
   // Make sure that the value transferred.
   Dart_Handle obj4 = Dart_HandleFromPersistent(obj3);
   EXPECT(Dart_IsBoolean(obj4));
   bool value = false;
   Dart_Handle result = Dart_BooleanValue(obj4, &value);
   EXPECT_VALID(result);
   EXPECT(value);
 }
 
 
+// Test that we can assign to a persistent handle.
+UNIT_TEST_CASE(AssignToPersistentHandle) {
+  const char* kTestString1 = "Test String1";
+  const char* kTestString2 = "Test String2";
+  TestIsolateScope __test_isolate__;
+
+  Isolate* isolate = Isolate::Current();
+  EXPECT(isolate != NULL);
+  ApiState* state = isolate->api_state();
+  EXPECT(state != NULL);
+  DARTSCOPE(isolate);
+  String& str = String::Handle();
+
+  // Start with a known persistent handle.
+  Dart_Handle ref1 = Api::NewHandle(isolate, String::New(kTestString1));
+  Dart_PersistentHandle obj = Dart_NewPersistentHandle(ref1);
+  EXPECT(state->IsValidPersistentHandle(obj));
+  str ^= Api::UnwrapAsPersistentHandle(obj)->raw();
+  EXPECT(str.Equals(kTestString1));
+
+  // Now create another local handle and assign it to the persistent handle.
+  Dart_Handle ref2 = Api::NewHandle(isolate, String::New(kTestString2));
+  Dart_Handle result = Dart_SetPersistentHandle(obj, ref2);
+  EXPECT_VALID(result);
+  str ^= Api::UnwrapAsPersistentHandle(obj)->raw();
+  EXPECT(str.Equals(kTestString2));
+
+  // Now assign Null to the persistent handle and check.
+  result = Dart_SetPersistentHandle(obj, Dart_Null());
+  EXPECT_VALID(result);
+  EXPECT(Dart_IsNull(obj));
+
+  // Negative test.
+  result = Dart_SetPersistentHandle(ref2, ref1);
+  EXPECT(Dart_IsError(result));
+}
+
+
 // Helper class to ensure new gen GC is triggered without any side effects.
 // The normal call to CollectGarbage(Heap::kNew) could potentially trigger
 // an old gen collection if there is a promotion failure and this could
 // perturb the test.
 class GCTestHelper : public AllStatic {
  public:
   static void CollectNewSpace(Heap::ApiCallbacks api_callbacks) {
     bool invoke_api_callbacks = (api_callbacks == Heap::kInvokeApiCallbacks);
     Isolate::Current()->heap()->new_space_->Scavenge(invoke_api_callbacks);
   }
@@ skipping 5887 matching lines @@
                                    NewString("main"),
                                    1,
                                    dart_args);
   int64_t value = 0;
   result = Dart_IntegerToInt64(result, &value);
   EXPECT_VALID(result);
   EXPECT_EQ(6, value);
 }
 
 }  // namespace dart