Add tests for ScopedCFTypeRef.

Copy the chromium pattern of taking Traits as template args to be
able to write a testable implementation of ScopedTypeRef.

Add unit tests for th current implementation.

Bug: webrtc:7825
Change-Id: I26017952c042c8323b9c3841ec309e32d1c04a85
Reviewed-on: https://webrtc-review.googlesource.com/5621
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20165}

sdk/objc/Framework/Classes/Common/scoped_cftyperef.h

@@ -15,25 +15,41 @@
 #include <CoreFoundation/CoreFoundation.h>
 namespace rtc {
 
-template <typename T>
-class ScopedCFTypeRef {
- public:
-  // RETAIN: ScopedCFTypeRef should retain the object when it takes
-  // ownership.
-  // ASSUME: Assume the object already has already been retained.
-  // ScopedCFTypeRef takes over ownership.
-  enum class RetainPolicy { RETAIN, ASSUME };
+// RETAIN: ScopedTypeRef should retain the object when it takes
+// ownership.
+// ASSUME: Assume the object already has already been retained.
+// ScopedTypeRef takes over ownership.
+enum class RetainPolicy { RETAIN, ASSUME };
 
-  ScopedCFTypeRef() : ptr_(nullptr) {}
-  explicit ScopedCFTypeRef(T ptr) : ptr_(ptr) {}
-  ScopedCFTypeRef(T ptr, RetainPolicy policy) : ScopedCFTypeRef(ptr) {
+namespace internal {
+template <typename T>
+struct CFTypeRefTraits {
+  static T InvalidValue() { return nullptr; }
+  static void Release(T ref) { CFRelease(ref); }
+  static T Retain(T ref) {
+    CFRetain(ref);
+    return ref;
+  }
+};
+
+template <typename T, typename Traits>
+class ScopedTypeRef {
+ public:
+  ScopedTypeRef() : ptr_(Traits::InvalidValue()) {}
+  explicit ScopedTypeRef(T ptr) : ptr_(ptr) {}
+  ScopedTypeRef(T ptr, RetainPolicy policy) : ScopedTypeRef(ptr) {
     if (ptr_ && policy == RetainPolicy::RETAIN)
-      CFRetain(ptr_);
+      Traits::Retain(ptr_);
   }
 
-  ~ScopedCFTypeRef() {
+  ScopedTypeRef(const ScopedTypeRef<T, Traits>& rhs) : ptr_(rhs.ptr_) {
+    if (ptr_)
+      ptr_ = Traits::Retain(ptr_);
+  }
+
+  ~ScopedTypeRef() {
     if (ptr_) {
-      CFRelease(ptr_);
+      Traits::Release(ptr_);
     }
   }
 
@@ -43,14 +59,14 @@ class ScopedCFTypeRef {
 
   bool operator!() const { return !ptr_; }
 
-  ScopedCFTypeRef& operator=(const T& rhs) {
+  ScopedTypeRef& operator=(const T& rhs) {
     if (ptr_)
-      CFRelease(ptr_);
+      Traits::Release(ptr_);
     ptr_ = rhs;
     return *this;
   }
 
-  ScopedCFTypeRef& operator=(const ScopedCFTypeRef<T>& rhs) {
+  ScopedTypeRef& operator=(const ScopedTypeRef<T, Traits>& rhs) {
     reset(rhs.get(), RetainPolicy::RETAIN);
     return *this;
   }
@@ -64,21 +80,26 @@ class ScopedCFTypeRef {
 
   void reset(T ptr, RetainPolicy policy = RetainPolicy::ASSUME) {
     if (ptr && policy == RetainPolicy::RETAIN)
-      CFRetain(ptr);
+      Traits::Retain(ptr);
     if (ptr_)
-      CFRelease(ptr_);
+      Traits::Release(ptr_);
     ptr_ = ptr;
   }
 
   T release() {
     T temp = ptr_;
-    ptr_ = nullptr;
+    ptr_ = Traits::InvalidValue();
     return temp;
   }
 
  private:
   T ptr_;
 };
+}  // namespace internal
+
+template <typename T>
+using ScopedCFTypeRef =
+    internal::ScopedTypeRef<T, internal::CFTypeRefTraits<T>>;
 
 template <typename T>
 static ScopedCFTypeRef<T> AdoptCF(T cftype) {

sdk/objc/Framework/UnitTests/scoped_cftyperef_tests.mm

@@ -0,0 +1,104 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "sdk/objc/Framework/Classes/Common/scoped_cftyperef.h"
+
+#include "test/gtest.h"
+
+namespace {
+struct TestType {
+  TestType() : has_value(true) {}
+  TestType(bool b) : has_value(b) {}
+  operator bool() { return has_value; }
+  bool has_value;
+  int retain_count = 0;
+};
+
+typedef TestType* TestTypeRef;
+
+struct TestTypeTraits {
+  static TestTypeRef InvalidValue() { return TestTypeRef(false); }
+  static void Release(TestTypeRef t) { t->retain_count--; }
+  static TestTypeRef Retain(TestTypeRef t) {
+    t->retain_count++;
+    return t;
+  }
+};
+}  // namespace
+
+using ScopedTestType = rtc::internal::ScopedTypeRef<TestTypeRef, TestTypeTraits>;
+
+// In these tests we sometime introduce variables just to
+// observe side-effects. Ignore the compilers complaints.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-variable"
+
+TEST(ScopedTypeRefTest, ShouldNotRetainByDefault) {
+  TestType a;
+  ScopedTestType ref(&a);
+  EXPECT_EQ(0, a.retain_count);
+}
+
+TEST(ScopedTypeRefTest, ShouldRetainWithPolicy) {
+  TestType a;
+  ScopedTestType ref(&a, rtc::RetainPolicy::RETAIN);
+  EXPECT_EQ(1, a.retain_count);
+}
+
+TEST(ScopedTypeRefTest, ShouldReleaseWhenLeavingScope) {
+  TestType a;
+  EXPECT_EQ(0, a.retain_count);
+  {
+    ScopedTestType ref(&a, rtc::RetainPolicy::RETAIN);
+    EXPECT_EQ(1, a.retain_count);
+  }
+  EXPECT_EQ(0, a.retain_count);
+}
+
+TEST(ScopedTypeRefTest, ShouldBeCopyable) {
+  TestType a;
+  EXPECT_EQ(0, a.retain_count);
+  {
+    ScopedTestType ref1(&a, rtc::RetainPolicy::RETAIN);
+    EXPECT_EQ(1, a.retain_count);
+    ScopedTestType ref2 = ref1;
+    EXPECT_EQ(2, a.retain_count);
+  }
+  EXPECT_EQ(0, a.retain_count);
+}
+
+TEST(ScopedTypeRefTest, CanReleaseOwnership) {
+  TestType a;
+  EXPECT_EQ(0, a.retain_count);
+  {
+    ScopedTestType ref(&a, rtc::RetainPolicy::RETAIN);
+    EXPECT_EQ(1, a.retain_count);
+    TestTypeRef b = ref.release();
+  }
+  EXPECT_EQ(1, a.retain_count);
+}
+
+TEST(ScopedTypeRefTest, ShouldBeTestableForTruthiness) {
+  ScopedTestType ref;
+  EXPECT_FALSE(ref);
+  TestType a;
+  ref = &a;
+  EXPECT_TRUE(ref);
+  ref.release();
+  EXPECT_FALSE(ref);
+}
+
+TEST(ScopedTypeRefTest, ShouldProvideAccessToWrappedType) {
+  TestType a;
+  ScopedTestType ref(&a);
+  EXPECT_EQ(&(a.retain_count), &(ref->retain_count));
+}
+
+#pragma clang diagnostic pop