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使用`unique_ptr`和`std::move`对象进行Google模拟,导致内存泄漏问题

googlemock unit-testing c++

Leonardo · 技术社区 · 4 月前

这个问题是对 Google mock with unique_ptr object giving memory leak issue 我所参加考试的班级承担了所有的责任 unique_ptr 关于其建筑商:

class Foo {
  public:
    virtual void doFoo() { std::cout << "Foo" << std::endl; }
};

class Bar {
  public:
    // So I can inject a mock Foo for testing
    Bar(std::unique_ptr<Foo> foo_)
        : foo_(std::move(foo_))
    {}

    Bar()
        : foo_(std::make_unique<Foo>())
    {}

    void doBar() { foo_->doFoo(); }

  private:
    std::unique_ptr<Foo> foo_;
};

class MockFoo : public Foo {
    MOCK_METHOD(void, doFoo, (), (override));
};

class FooTest : public ::testing::Test {
  public:
    void SetUp() override
    {
        mockFoo = std::make_unique<NiceMock<MockFoo>>();
    }

    std::unique_ptr<NiceMock<MockFoo>> mockFoo;
    NiceMock<MockFoo>* mockFooPtr;
};

TEST_F(FooTest, foo)
{
    using ::testing::NiceMock;

    // This will fail on purpose
    EXPECT_CALL(*mockFoo, doFoo()).Times(2);

    mockFooPtr = mockFoo.get();

    Bar bar(std::move(mockFoo));
    bar.doBar();

    EXPECT_TRUE(testing::Mock::VerifyAndClearExpectations(mockFooPtr));
}

在运行该测试时,我得到

ERROR: this mock object (used in test FooTest.foo) should be deleted but never is. Its address is @0x5ccb272fba60.
3: ERROR: 1 leaked mock object found at program exit. Expectations on a mock object are verified when the object is destructed. Leaking a mock means that its expectations aren't verified, which is usually a test bug. If you really intend to leak a mock, you can suppress this error using testing::Mock::AllowLeak(mock_object), or you may use a fake or stub instead of a mock.

所以 VerifyAndClearExpectations 不起作用。问题是所有权转移。如果 Bar 更新以获取原始指针,没有模拟泄漏错误:

class Bar {
  public:
    Bar(Foo* foo_)
        : foo_(foo_)
    {}

    void doBar() { foo_->doFoo(); }

  private:
    Foo* foo_;
};

TEST_F(FooTest, foo)
{
    using ::testing::NiceMock;


    // This will fail on purpose
    EXPECT_CALL(*mockFoo, doFoo()).Times(1);

    mockFooPtr = mockFoo.get();

    // Bar bar(std::move(mockFoo));
    Bar bar(mockFoo.get());
    bar.doBar();
}

我必须使用 std::move 因为这就是生产代码所期望的。

根据下面的评论,我尝试将测试更新为:

TEST_F(FooTest, foo)
{
    // This will fail on purpose
    EXPECT_CALL(*mockFoo, doFoo()).Times(2);

    mockFooPtr = mockFoo.get();
    {
        Bar bar(std::move(mockFoo));
        bar.doBar();
        EXPECT_TRUE(testing::Mock::VerifyAndClearExpectations(mockFooPtr));
    }
}

我仍然会收到一个模拟泄漏错误。

谢谢!

1 回复 | 直到 4 月前

JaMiT 4 月前

多态对象应该有一个虚拟析构函数。如果不这样做,那么通过基类指针的所有权在销毁时会导致未定义的行为,因为只有基类析构函数会运行。特别是,使用您的代码,销毁 std::unique_ptr<Foo> 不调用 ~MockFoo() 即使托管对象实际上是 MockFoo .

要获得所需的行为,请添加虚拟析构函数:

class Foo {
  public:
    virtual ~Foo() = default; // <-- Add this line

    virtual void doFoo() { std::cout << "Foo" << std::endl; }
};

请参阅 When to use virtual destructors?