如何用C++测试具有多个模板参数的GTest模板类？

Question

我有个小班：

template <class key_t, class value_t>
class node_t {
public:
    node_t();
    void set_key(key_t);
    key_t get_key();
    void set_value(value_t);
    value_t get_value();

private:
    key_t key;
    value_t value;
};

template <class key_t, class value_t>
node_t<key_t, value_t>::node_t() {
    key = (key_t)0;
    value = (value_t)0;
}

template <class key_t, class value_t>
void node_t<key_t, value_t>::set_key(key_t key) {
    this->key = key;
}

template <class key_t, class value_t>
key_t node_t<key_t, value_t>::get_key() {
    return this->key;
}

template <class key_t, class value_t>
void node_t<key_t, value_t>::set_value(value_t value) {
    this->value = value;
}

template <class key_t, class value_t>
value_t node_t<key_t, value_t>::get_value() {
    return this->value;
}

我如何用Google测试框架来测试它呢？

/*
TEST(node_test_t, node_test) {
    node_t<std::string, float> node;

    std::string key = node.get_key();
    ASSERT_STREQ(key, 0);

    node.set_key("one");
    ASSERT_STREQ(node.get_key(), "one");

    float value = node.get_value();
    ASSERT_EQ(value, 0);

    node.set_value(2.4);
    ASSERT_EQ(node.get_value(), 2.4);
}
*/

// Updated
TEST(node_test_t, node_test)
{
    node_t<std::string, float> node;

    std::string key = node.get_key();
    ASSERT_STREQ("0", key.c_str());

    node.set_key("one");
    ASSERT_STREQ("one", node.get_key().c_str());

    float value = node.get_value();
    ASSERT_EQ(value, 0);

    node.set_value(2.4f);
    ASSERT_EQ(node.get_value(), 2.4f);
}

我还发现：

• How to test c++ template class with multiple template parameters using gtest?
• gtest - testing template class
• unittest.cc 但我无法编译结果。请展示一个简单的例子，我可以使用Google测试框架为这个类编写测试。

UPD:我也尝试过这个：https://groups.google.com/forum/#!searchin/googletestframework/class$20template/googletestframework/wSlsjwU7vls/9ulYoFliuLgJ

template <class key_t, class value_t>
class node_testing_t : public node_t<key_t, value_t> {
public:
    using node_t<key_t, value_t>::get_value;
};

TEST(node_test_case, get_value) {
    node_testing_t<std::string, float> node_testing;
    ASSERT_EQ(0, node_testing.get_value());
}

我也有LNK2019错误：

1>------ Skipped Build: Project: RUN_TESTS, Configuration: Debug Win32 ------
1>Project not selected to build for this solution configuration 
2>------ Build started: Project: googlemock, Configuration: Debug Win32 ------
3>------ Build started: Project: tests, Configuration: Debug Win32 ------
3>node_test.obj : error LNK2019: unresolved external symbol "public: __thiscall node_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>::node_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>(void)" (??0?$node_t@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@M@@QAE@XZ) referenced in function "public: __thiscall node_testing_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>::node_testing_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>(void)" (??0?$node_testing_t@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@M@@QAE@XZ)
3>node_test.obj : error LNK2019: unresolved external symbol "public: __thiscall node_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>::~node_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>(void)" (??1?$node_t@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@M@@QAE@XZ) referenced in function "public: __thiscall node_testing_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>::~node_testing_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>(void)" (??1?$node_testing_t@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@M@@QAE@XZ)
3>node_test.obj : error LNK2019: unresolved external symbol "public: float __thiscall node_t<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,float>::get_value(void)" (?get_value@?$node_t@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@M@@QAEMXZ) referenced in function "private: virtual void __thiscall node_test_case_get_value_Test::TestBody(void)" (?TestBody@node_test_case_get_value_Test@@EAEXXZ)
3>C:\Users\user\Desktop\hill-climbing\bin\tests.exe : fatal error LNK1120: 3 unresolved externals
4>------ Skipped Build: Project: ALL_BUILD, Configuration: Debug Win32 ------
4>Project not selected to build for this solution configuration 
========== Build: 1 succeeded, 1 failed, 2 up-to-date, 2 skipped ==========

Answer 1

我在Linux4.8.4上尝试了您的示例，链接没有问题，尽管测试执行失败了，因为node对象构造会抛出一个异常，因为构造函数中的key = (key_t)0行试图将一个0转换为std::string对象。

尽管如此，在您的示例中，MSVC链接器抱怨说，在node_test.obj文件中有未解决的对与node_t<std::string, float>相关的符号的引用，即构造函数、析构函数和get_value()成员函数。只是你测试中用到的那些。

在测试用例的范围内实例化模板，尝试在外部范围内执行。

using node_string_float_t = node_t<std::string, float>;

TEST(node_test_t, node_test)
{
    node_string_float_t node;

    std::string key = node.get_key();
    ASSERT_STREQ("0", key.c_str());

    node.set_key("one");
    ASSERT_STREQ("one", node.get_key().c_str());

    float value = node.get_value();
    ASSERT_EQ(value, 0);

    node.set_value(2.4f);
    ASSERT_EQ(node.get_value(), 2.4f);
}

Answer 2

你读过ASSERT_STREQ文档吗？这个宏接受两个C-strings，您试图首先传递它std::string和int，在第二种情况下传递std::string和C-string。顺便说一下，第一个参数是期望值，第二个参数是实际值，所以您可能需要切换提供参数的顺序。

TEST(node_test_t, node_test)
{
    node_t<std::string, float> node;

    std::string key = node.get_key();
    ASSERT_STREQ("0", key.c_str());

    node.set_key("one");
    ASSERT_STREQ("one", node.get_key().c_str());

    float value = node.get_value();
    ASSERT_EQ(value, 0);

    node.set_value(2.4f);
    ASSERT_EQ(node.get_value(), 2.4f);
}

P.S.如果您想比较std::string对象，可以使用EXPECT_EQ、EXPECT_NE等等。