Google單元測試框架gtest之官方sample筆記4--事件監控之記憶體洩漏測試
阿新 • • 發佈：2021-03-04
sample 10 使用event listener監控Water類的建立和銷燬。在Water類中，有一個靜態變數allocated，建立一次值加一，銷燬一次值減一。為了實現這個功能，過載了new和delete關鍵字，然後在new和delete函式中，做allocated的增減和記錄allocated變數的值。
class Water {
public:
// Normal Water declarations go here.
// operator new and operator delete help us control water allocation.
void* operator new(size_t allocation_size) {
allocated_++;
return malloc(allocation_size);
}
void operator delete(void* block, size_t /* allocation_size */) {
allocated_--;
free(block);
}
static int allocated() { return allocated_; }
private:
static int allocated_;
};
int Water::allocated_ = 0;gtest的event listener能在TEST執行前和執行後呼叫，然後就可以判斷TEST執行完後是否發生洩漏。event listner是非入侵式檢測，不需要在TEST裡寫測試程式碼，而是在TEST之外執行特定的監控程式碼。
註冊event監聽的方法如下，在每個測試前執行OnTestStart，在測試後執行OnTestEnd。計算int difference = Water::allocated() - initially_allocated_;就可以得知是否發生記憶體洩漏，忘記了刪除new的物件。
class LeakChecker : public EmptyTestEventListener {
private:
// Called before a test starts.
void OnTestStart(const TestInfo& test_info ) override {
initially_allocated_ = Water::allocated();
}
// Called after a test ends.
void OnTestEnd(const TestInfo& /* test_info */) override {
int difference = Water::allocated() - initially_allocated_;
// You can generate a failure in any event handler except
// OnTestPartResult. Just use an appropriate Google Test assertion to do
// it.
EXPECT_LE(difference, 0) << "Leaked " << difference << " unit(s) of Water!";
}
int initially_allocated_;
};
// 如果檢查洩漏，則註冊event listener監控
if (check_for_leaks) {
TestEventListeners& listeners = UnitTest::GetInstance()->listeners();
listeners.Append(new LeakChecker);
}測試程式碼如下，由於使用的是非入侵式檢測，所以TEST函式和普通的測試一樣。下面的DoesNotLeak測試無記憶體洩漏發生，而LeaksWater測試，會發生記憶體洩漏。
TEST(ListenersTest, DoesNotLeak) {
Water* water = new Water;
delete water;
}
// This should fail when the --check_for_leaks command line flag is specified.
TEST(ListenersTest, LeaksWater) {
Water* water = new Water;
EXPECT_TRUE(water != nullptr);
}不啟用記憶體洩漏測試時的輸出結果：
使用記憶體洩漏測試時的輸出結果：
尊重技術文章，轉載請註明！
Google單元測試框架gtest之官方sample筆記4--事件監控之記憶體洩漏測試
https://www.cnblogs.com/pingwen/p/14482187.html