如何仅覆盖一个EXPECT_CALL的默认ON_CALL操作，稍后再返回到默认操作

问：

我想测试我的系统的方法，其返回值部分取决于对某种连接接口的调用的返回值。在大多数情况下，我希望在对它的方法进行任何形式的调用时返回。除了一种情况，当我显式测试连接失败的条件时。IConnectiontrueopen(_, _)

例：

/*
 * Some kind of network interface with method `open`
 */
class IConnection {
public:
    IConnection() = default;
    virtual ~IConnection() = default;
    virtual bool open(const std::string& address, int port) = 0;
};

class ConnectionMock: public IConnection {
public:
    MOCK_METHOD2(open, bool(const std::string& address, int port));
};

class MySystem {
public:
    MySystem() = delete;
    MySystem(std::shared_ptr<IConnection> connection): connection_(connection) {}
    bool doSth() {
        /*
         * Do some things, but fail if connection fails
         */
        bool connectionStatus = connection_->open("127.0.0.1", 6969);
        if (!connectionStatus) {
            return false;
        }
        // do other things
        return true;
    }
private:
    std::shared_ptr<IConnection> connection_;
};

TEST(MySystemShould, returnFalseIfFailedToOpenConnectionAndTrueIfSucceeded) {
    auto connectionMock = std::make_shared<NiceMock<ConnectionMock> >();
    ON_CALL(*connectionMock, open(_, _)).WillByDefault(Return(true));
    MySystem system(connectionMock);
    // if I don't specify Times test fill fail, because WillOnce automatically sets Times(1)
    EXPECT_CALL(*connectionMock, open(_, _)).Times(AnyNumber()).WillOnce(Return(false));
    /*
     * Commented code below is not a good solution - after expectation retires
     * the test will fail upon subsequent calls
     */
    //EXPECT_CALL(*connectionMock, open(_, _)).WillOnce(Return(false)).RetiresOnSaturation();
    ASSERT_FALSE(system.doSth());
    /*
     * Code bellow allows me to avoid the warning
     */
    //EXPECT_CALL(*connectionMock, open(_, _)).WillRepeatedly(Return(true));
    ASSERT_TRUE(system.doSth());
}

我当前解决方案的问题是，当覆盖变得饱和时，即使 gmock 返回到 上指定的默认操作，每次后续调用都会导致以下警告：EXPECT_CALLON_CALLopen(_, _)

GMOCK WARNING:
/whatever.cpp:105: Actions ran out in EXPECT_CALL(*connectionMock, open(_, _))...
Called 2 times, but only 1 WillOnce() is specified - taking default action specified at:
/whatever.cpp:103:

即使我正在使用 .我可以通过指定 来摆脱警告，但这是我在 中的代码的重复。NiceMockEXPECT_CALLWillRepeatedly(Return(true))ON_CALL

我想知道，我怎样才能覆盖仅为一次调用指定的默认操作，然后返回默认值，而不会导致 gmock 打印警告。完美的解决方案类似于：ON_CALLIConnection::open

EXPECT_CALL(*connectionMock, open(_, _)).WillOnce(Return(false)).DisableExpectationAfterSaturation();

但它并不存在。 无法如我所愿，因为它在饱和后无法通过测试（与指定的操作不匹配）。RetiresOnSaturationON_CALL