Add unit test for AutoRestorer<> on smart pointer types.

Test UnownedPtr<> and RetainPtr<>. We cannot operate against
std::unique_ptr<> because we need a copyable type. Add test for
self-reassignment on going out of scope. Move one test helper
class to testing/ so it can be shared among unit tests. Allow it
to recognize if it ever gets "destroyed", otherwise we can't be
sure Retain/Release applied in the correct order.

Change-Id: I13056094c70079f7283cbc7600948f81a64874b4
Reviewed-on: https://pdfium-review.googlesource.com/41690
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/testing/pseudo_retainable.h b/testing/pseudo_retainable.h
new file mode 100644
index 0000000000..c4390d697d
--- /dev/null
+++ b/testing/pseudo_retainable.h
@@ -0,0 +1,26 @@
+// Copyright 2018 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef TESTING_PSEUDO_RETAINABLE_H_
+#define TESTING_PSEUDO_RETAINABLE_H_
+
+class PseudoRetainable {
+ public:
+  PseudoRetainable() = default;
+  void Retain() { ++retain_count_; }
+  void Release() {
+    if (++release_count_ == retain_count_)
+      alive_ = false;
+  }
+  bool alive() const { return alive_; }
+  int retain_count() const { return retain_count_; }
+  int release_count() const { return release_count_; }
+
+ private:
+  bool alive_ = true;
+  int retain_count_ = 0;
+  int release_count_ = 0;
+};
+
+#endif  // TESTING_PSEUDO_RETAINABLE_H_