Google Test返回正常运行的垃圾值

Question

我已经在主文件中手动测试了.decreaseInventory（），所以我知道它可以正常工作，但是当我对其执行google测试时，它失败并给我一个错误。我该如何解决？

播放器类：

#ifndef PLAYER_H
#define PLAYER_H

#include <iostream>  
using namespace std;

class Player
{

    int inventory;

public:
    Player();
    int decreaseInventory(int numOfBeers);
    int increaseInventory(int numOfBeers);
    void setInventory(int newInventory);
    int getBackOrder();
    int getCost();
    int getInventory();

    bool operator ==(Player& p);
};

Player::Player()
{
    cout << " Default Player Constructor\n";
    inventory = 12;
    backorder = 0;
    cost = 0;
    orderDelay = 0;
    shipmentDeplay = 0;
}

void Player::setInventory(int newInventory)
{
    inventory = newInventory;
}

int Player::decreaseInventory(int numOfBeers)
{
    inventory = inventory - numOfBeers;
}

int Player::increaseInventory(int numOfBeers)
{
    inventory = inventory + numOfBeers;
}
int Player::getInventory()
{
    return inventory;
}

test.cpp：

#include "gtest/gtest.h"
#include "Player.h"

TEST(playerTest, decreaseInventoryTest ) {

    Player p;
    int curr_inv = p.getInventory();
    EXPECT_EQ(curr_inv-3, p.decreaseInventory(3));

}

错误：

Running main() from gtest_main.cc
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from playerTest
[ RUN      ] playerTest.decreaseInventoryTest
 Default Player Constructor
/home/s/s/tests.cpp:13: Failure
      Expected: curr_inv-3
      Which is: 9
To be equal to: p.decreaseInventory(3)
      Which is: 1740894128
[  FAILED  ] playerTest.decreaseInventoryTest (1 ms)
[----------] 1 test from playerTest (1 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (1 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] playerTest.decreaseInventoryTest

 1 FAILED TEST

为什么它会失败并给出垃圾值？我已经在使用默认构造函数，并且通常它可以正常工作。

编辑：现在可以正常工作，但是如果我在一个测试中有两个测试，它将失败。例如：如果我注释掉第二个，但是如果我都尝试了，则它们将失败并给出此错误：

测试：

TEST(playerTest, increaseInventoryTest) {

    Player p;
    int curr_inv = p.getInventory();
    EXPECT_EQ(curr_inv+3, p.increaseInventory(3));
    EXPECT_EQ(curr_inv+1000000, p.increaseInventory(1000000));
}

错误：

 Default Player Constructor
/home/s/s/tests.cpp:22: Failure
      Expected: curr_inv+1000000
      Which is: 1000012
To be equal to: p.increaseInventory(1000000)
      Which is: 1000015
[  FAILED  ] playerTest.increaseInventoryTest (0 ms)
[----------] 2 tests from playerTest (0 ms total)

[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran. (0 ms total)
[  PASSED  ] 1 test.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] playerTest.increaseInventoryTest

 1 FAILED TEST

为什么在进行两次测试时行为会有所不同？

Answer 1

您的方法是：

int Player::decreaseInventory(int numOfBeers)
{
    inventory = inventory - numOfBeers;
}

您的测试是：

EXPECT_EQ(curr_inv-3, p.decreaseInventory(3));

宏EXPECT_EQ将p.decreaseInventory(3)返回的值与curr_inv-3进行比较。该方法不返回任何内容。

不从已声明要返回内容的方法中返回内容是未定义的行为。您的编译器应该已经对此发出警告，并且您的测试失败了，因为您的测试失败是由代码中的实际错误引起的，您现在可以对其进行修复。

Answer 2

您在decreaseInventory函数定义中缺少返回值。要解决此问题，只需返回inventory成员变量的（已修改）值：

int Player::decreaseInventory(int numOfBeers)
{
    inventory = inventory - numOfBeers;
    return inventory; // You need to return the modified value!
}