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>

4 files changed, 171 insertions, 16 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 27e4b2615a..1d4573a8f2 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -3047,6 +3047,7 @@ test("pdfium_embeddertests") {
     "testing/embedder_test_timer_handling_delegate.h",
     "testing/fake_file_access.cpp",
     "testing/fake_file_access.h",
+    "testing/pseudo_retainable.h",
     "testing/range_set.cpp",
     "testing/range_set.h",
   ]
diff --git a/core/fxcrt/autorestorer_unittest.cpp b/core/fxcrt/autorestorer_unittest.cpp
index ac1d613e7c..6430fb67f6 100644
--- a/core/fxcrt/autorestorer_unittest.cpp
+++ b/core/fxcrt/autorestorer_unittest.cpp
@@ -3,7 +3,10 @@
 // found in the LICENSE file.
 
 #include "core/fxcrt/autorestorer.h"
+#include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/unowned_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "testing/pseudo_retainable.h"
 
 TEST(fxcrt, AutoRestorer) {
   int x = 5;
@@ -13,6 +16,19 @@ TEST(fxcrt, AutoRestorer) {
     EXPECT_EQ(6, x);
   }
   EXPECT_EQ(5, x);
+}
+
+TEST(fxcrt, AutoRestorerNoOp) {
+  int x = 5;
+  {
+    AutoRestorer<int> restorer(&x);
+    EXPECT_EQ(5, x);
+  }
+  EXPECT_EQ(5, x);
+}
+
+TEST(fxcrt, AutoRestorerAbandon) {
+  int x = 5;
   {
     AutoRestorer<int> restorer(&x);
     x = 6;
@@ -21,3 +37,130 @@ TEST(fxcrt, AutoRestorer) {
   }
   EXPECT_EQ(6, x);
 }
+
+TEST(fxcrt, AutoRestorerUnownedPtr) {
+  int x = 5;
+  int y = 6;
+  UnownedPtr<int> ptr(&x);
+  {
+    AutoRestorer<UnownedPtr<int>> restorer(&ptr);
+    ptr = &y;
+    EXPECT_EQ(&y, ptr);
+  }
+  EXPECT_EQ(&x, ptr);
+}
+
+TEST(fxcrt, AutoRestorerUnownedNoOp) {
+  int x = 5;
+  UnownedPtr<int> ptr(&x);
+  {
+    AutoRestorer<UnownedPtr<int>> restorer(&ptr);
+    EXPECT_EQ(&x, ptr);
+  }
+  EXPECT_EQ(&x, ptr);
+}
+
+TEST(fxcrt, AutoRestorerUnownedPtrAbandon) {
+  int x = 5;
+  int y = 6;
+  UnownedPtr<int> ptr(&x);
+  {
+    AutoRestorer<UnownedPtr<int>> restorer(&ptr);
+    ptr = &y;
+    EXPECT_EQ(&y, ptr);
+    restorer.AbandonRestoration();
+  }
+  EXPECT_EQ(&y, ptr);
+}
+
+TEST(fxcrt, AutoRestorerRetainPtr) {
+  PseudoRetainable obj1;
+  PseudoRetainable obj2;
+  RetainPtr<PseudoRetainable> ptr(&obj1);
+  EXPECT_EQ(1, obj1.retain_count());
+  EXPECT_EQ(0, obj1.release_count());
+  {
+    AutoRestorer<RetainPtr<PseudoRetainable>> restorer(&ptr);
+    // |obj1| is kept alive by restorer in case it need to be restored.
+    EXPECT_EQ(2, obj1.retain_count());
+    EXPECT_EQ(0, obj1.release_count());
+    ptr.Reset(&obj2);
+    EXPECT_EQ(&obj2, ptr.Get());
+
+    // |obj1| released by |ptr| assignment.
+    EXPECT_TRUE(obj1.alive());
+    EXPECT_EQ(2, obj1.retain_count());
+    EXPECT_EQ(1, obj1.release_count());
+
+    // |obj2| now kept alive by |ptr|.
+    EXPECT_TRUE(obj1.alive());
+    EXPECT_EQ(1, obj2.retain_count());
+    EXPECT_EQ(0, obj2.release_count());
+  }
+  EXPECT_EQ(&obj1, ptr.Get());
+
+  // |obj1| now kept alive again by |ptr|.
+  EXPECT_TRUE(obj1.alive());
+  EXPECT_EQ(3, obj1.retain_count());
+  EXPECT_EQ(2, obj1.release_count());
+
+  // |obj2| dead.
+  EXPECT_FALSE(obj2.alive());
+  EXPECT_EQ(1, obj2.retain_count());
+  EXPECT_EQ(1, obj2.release_count());
+}
+
+TEST(fxcrt, AutoRestorerRetainPtrNoOp) {
+  PseudoRetainable obj1;
+  RetainPtr<PseudoRetainable> ptr(&obj1);
+  EXPECT_EQ(1, obj1.retain_count());
+  EXPECT_EQ(0, obj1.release_count());
+  {
+    AutoRestorer<RetainPtr<PseudoRetainable>> restorer(&ptr);
+    EXPECT_EQ(2, obj1.retain_count());
+    EXPECT_EQ(0, obj1.release_count());
+  }
+  EXPECT_EQ(&obj1, ptr.Get());
+
+  // Self-reassignement avoided ref churn.
+  EXPECT_TRUE(obj1.alive());
+  EXPECT_EQ(2, obj1.retain_count());
+  EXPECT_EQ(1, obj1.release_count());
+}
+
+TEST(fxcrt, AutoRestorerRetainPtrAbandon) {
+  PseudoRetainable obj1;
+  PseudoRetainable obj2;
+  RetainPtr<PseudoRetainable> ptr(&obj1);
+  EXPECT_EQ(1, obj1.retain_count());
+  EXPECT_EQ(0, obj1.release_count());
+  {
+    AutoRestorer<RetainPtr<PseudoRetainable>> restorer(&ptr);
+    // |obj1| is kept alive by restorer in case it need to be restored.
+    EXPECT_EQ(2, obj1.retain_count());
+    EXPECT_EQ(0, obj1.release_count());
+    ptr.Reset(&obj2);
+    EXPECT_EQ(&obj2, ptr.Get());
+
+    // |obj1| released by |ptr| assignment.
+    EXPECT_EQ(2, obj1.retain_count());
+    EXPECT_EQ(1, obj1.release_count());
+
+    // |obj2| now kept alive by |ptr|.
+    EXPECT_EQ(1, obj2.retain_count());
+    EXPECT_EQ(0, obj2.release_count());
+
+    restorer.AbandonRestoration();
+  }
+  EXPECT_EQ(&obj2, ptr.Get());
+
+  // |obj1| now dead as a result of abandonment.
+  EXPECT_FALSE(obj1.alive());
+  EXPECT_EQ(2, obj1.retain_count());
+  EXPECT_EQ(2, obj1.release_count());
+
+  // |obj2| kept alive by |ptr|.
+  EXPECT_TRUE(obj2.alive());
+  EXPECT_EQ(1, obj2.retain_count());
+  EXPECT_EQ(0, obj2.release_count());
+}
diff --git a/core/fxcrt/retain_ptr_unittest.cpp b/core/fxcrt/retain_ptr_unittest.cpp
index f4b2994eae..5548e9bfd7 100644
--- a/core/fxcrt/retain_ptr_unittest.cpp
+++ b/core/fxcrt/retain_ptr_unittest.cpp
@@ -8,24 +8,9 @@
 #include <vector>
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "testing/pseudo_retainable.h"
 
 namespace fxcrt {
-namespace {
-
-class PseudoRetainable {
- public:
-  PseudoRetainable() : retain_count_(0), release_count_(0) {}
-  void Retain() { ++retain_count_; }
-  void Release() { ++release_count_; }
-  int retain_count() const { return retain_count_; }
-  int release_count() const { return release_count_; }
-
- private:
-  int retain_count_;
-  int release_count_;
-};
-
-}  // namespace
 
 TEST(RetainPtr, Null) {
   RetainPtr<PseudoRetainable> ptr;
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_