mojo: Don't leak handles when assigning to ScopedHandles.

mojo/public/cpp/system/tests/core_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file tests the C++ Mojo system core wrappers.
 // TODO(vtl): Maybe rename "CoreCppTest" -> "CoreTest" if/when this gets
 // compiled into a different binary from the C API tests.
 
 #include "mojo/public/cpp/system/core.h"
 
@@ skipping 368 matching lines @@
                               MOJO_WRITE_MESSAGE_FLAG_NONE));
     // |h3_value| should actually be invalid now.
     EXPECT_EQ(MOJO_RESULT_INVALID_ARGUMENT, MojoClose(h3_value));
 
     EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h2.release().value()));
     EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h0.release().value()));
     EXPECT_EQ(MOJO_RESULT_OK, MojoClose(h1.release().value()));
   }
 }
 
+TEST(CoreCppTest, ScopedHandleMoveCtor) {
+  ScopedSharedBufferHandle buffer1;
+  EXPECT_EQ(MOJO_RESULT_OK, CreateSharedBuffer(NULL, 1024, &buffer1));
+  EXPECT_TRUE(buffer1.is_valid());
+
+  ScopedSharedBufferHandle buffer2;
+  EXPECT_EQ(MOJO_RESULT_OK, CreateSharedBuffer(NULL, 1024, &buffer2));
+  EXPECT_TRUE(buffer2.is_valid());
+
+  // If this fails to close buffer1, ScopedHandleBase::CloseIfNecessary() will
+  // assert.
+  buffer1 = buffer2.Pass();
+
+  EXPECT_TRUE(buffer1.is_valid());
+  EXPECT_FALSE(buffer2.is_valid());
+}
+
+TEST(CoreCppTest, ScopedHandleMoveCtorSelf) {
+  ScopedSharedBufferHandle buffer1;
+  EXPECT_EQ(MOJO_RESULT_OK, CreateSharedBuffer(NULL, 1024, &buffer1));
+  EXPECT_TRUE(buffer1.is_valid());
+
+  buffer1 = buffer1.Pass();
+
+  EXPECT_TRUE(buffer1.is_valid());
+}
+
 // TODO(vtl): Write data pipe tests.
 
 }  // namespace
 }  // namespace mojo