Google单元测试框架gtest之官方sample笔记4--事件监控之内存泄漏测试
sample 10 使用event listener监控Water类的创建和销毁。在Water类中,有一个静态变量allocated,创建一次值加一,销毁一次值减一。为了实现这个功能,重载了new和delete关键字,然后在new和delete函数中,
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执行前和执行后调用,然后就可以判断TEST执行完后是否发生泄漏。event listner是非入侵式检测,不需要在TEST里写测试代码,而是在TEST之外执行特定的监控代码。
注册event监听的方法如下,在每个测试前执行OnTestStart,在测试后执行OnTestEnd。计算int difference = Water::allocated() - initially_allocated_;就可以得知是否发生内存泄漏,忘记了删除new的对象。
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_; }; // 如果检查泄漏,则注册event listener监控 if (check_for_leaks) { TestEventListeners& listeners = UnitTest::GetInstance()->listeners(); listeners.Append(new LeakChecker); }
测试代码如下,由于使用的是非入侵式检测,所以TEST函数和普通的测试一样。下面的DoesNotLeak测试无内存泄漏发生,而LeaksWater测试,会发生内存泄漏。
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); }
不启用内存泄漏测试时的输出结果:
使用内存泄漏测试时的输出结果:
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Google单元测试框架gtest之官方sample笔记4--事件监控之内存泄漏测试