Get GenericScopedHandle::Set to preserve LastError code

base/win/scoped_handle_unittest.cc

Index: base/win/scoped_handle_unittest.cc
diff --git a/base/win/scoped_handle_unittest.cc b/base/win/scoped_handle_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b683021f68191e0ad2b0ecf396050a63a914f375
--- /dev/null
+++ b/base/win/scoped_handle_unittest.cc
@@ -0,0 +1,38 @@
+// Copyright (c) 2011 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.
+
+#include "base/win/scoped_handle.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace win {

[rvargas (doing something else), 2015/09/10 22:42:02]

nit: Could you remove these namespaces?

long reason: I don't like to place tests under the same namespace of the code
under test because when someone is going through a random test to figure out why
it is failing, being as explicit as possible about where the code comes from is
a good thing. It may not be much of an issue in this specific case, but code may
come from the test file's anon namespace, or from the code under test, or from
the OS, or from any other file/library included here (more of an issue for tests
outside of base, but still).

It may be harder to write, but it is easier on the reader.

[brucedawson, 2015/09/10 23:21:46]

We should probably do a code-cleanup pass at some point because about two thirds
of base\win\*unittest.cc files use base\win namespaces.

+
+TEST(ScopedHandleTest, ScopedHandle) {
+  // Any illegal error code will do. We just need to test that it is preserved
+  // by ScopedHandle to avoid bug 528394.
+  const DWORD magic_error = 0x12345678;
+
+  HANDLE handle = CreateMutex(nullptr, FALSE, nullptr);

[rvargas (doing something else), 2015/09/10 22:42:02]

nit: related to the previous one... use ::CreateMutex (etc)

[brucedawson, 2015/09/10 23:21:46]

Done, for CreateMutex(), SetLastError(), and GetLastError(), for all three
sub-tests.

+  // Call SetLastError after creating the handle.
+  SetLastError(magic_error);
+  ScopedHandle handle_holder(handle);
+  EXPECT_EQ(magic_error, GetLastError());
+
+  // Create a new handle and then set LastError again.
+  handle = CreateMutex(nullptr, FALSE, nullptr);
+  SetLastError(magic_error);
+  handle_holder.Set(handle);
+  EXPECT_EQ(magic_error, GetLastError());
+
+  // Create a new handle and then set LastError again.
+  handle = CreateMutex(nullptr, FALSE, nullptr);
+  ScopedHandle handle_source(handle);
+  SetLastError(magic_error);
+  handle_holder = std::move(handle_source);
+  EXPECT_EQ(magic_error, GetLastError());
+}
+
+}  // namespace win
+}  // namespace base