数据驱动的单元测试与Google Test [英] Data-driven unit tests with google test

问题描述

我目前正在使用 googles单元测试框架为嵌入式应用程序编写单元测试。现在我的老板很沮丧，我在测试中硬连接了我测试的数据（即我用来调用被测类的方法的值）。他要求从文件中读取此数据。他的论点是，为以前被遗忘的极端情况添加另一个测试会更容易。我没有单元测试的经验，但是到目前为止，这还不是我的经验。因此，我试图弄清楚什么是最好的方法-即使完全是个好主意。我很快就想到了DDT（数据驱动测试）方法。

I am currently writing unit tests for an embedded application using googles unit test framework. Now my boss got upset that the data I test with (i.e. the values with which I call methods of the class under test) is hard wired in the tests. He requests to have this data read-in from a file. His argument is that it would thus be easier to add another test for a corner case that was previously forgotten. I am not that experienced with unit tests but so far that was not how I did it. So I tried to figure out what would be the best way to do it - even if it is a good idea to do it at all. I quickly came across the DDT (data-driven testing) approach.

google单元测试框架具有一个称为 值参数化测试。这样，我的测试装置便成为模板类，并且可以传递参数。但是，我看到了一些问题：

The google unit test framework has a feature they call "Value-Parameterized Tests". With that my test fixture becomes a template class and I can pass in parameters. However, I see some problems with this:

• 我目前正在测试每个班级的灯具。但由于每种方法都需要一组不同的参数，因此每种测试方法都需要一个夹具。


• 如我所见，我只能传递一个参数。由于我的测试需要几个参数（方法的所有参数加上预期的结果），这将要求我传递矢量或映射之类的信息。再次，这种构造和检索听起来像是很多工作。

我原本以为可以像Google测试框架一样成熟更容易。但是，他们编写了

I would have imagined that something as mature as the google test framework to make it easier. However, they write

值参数化的测试很方便[当您想通过各种输入来测试代码时（也就是数据驱动的测试） ）。此功能易于滥用，因此在执行此操作时请多加注意！

value-parameterized tests come handy [when] you want to test your code over various inputs (a.k.a. data-driven testing). This feature is easy to abuse, so please exercise your good sense when doing it!

此外，此博客文章 TotT：数据驱动陷阱，也警告我（滥用）数据-驱动单元测试。

Additionally there exists this blogpost TotT: Data Driven Traps, also warning me of (abusing) data-driven unit tests.

所以我的问题归结为：

• 是吗进行数据驱动的单元测试的好主意？


• 如何使用Google测试框架进行数据驱动的单元测试

我并不是真正地受googletest的束缚，但是基本上可以自由选择我想要的任何框架。

I am not really bound to googletest and basically free to choose any framework I'd like, though.

编辑

我在googletest常见问题解答的FAQ条目中找到了以下语句

I found the following statement in an FAQ entry of the googletest FAQs

总体而言，Google Test还没有对数据驱动测试的良好支持。我们希望能够尽快在这方面进行改进。

Google Test doesn't yet have good support for [...] data-driven tests in general. We hope to be able to make improvements in this area soon.

推荐答案

GTest支持它-但也许他们不知道...

GTest has support for it - but maybe they do not know...

使用 testing :: ValuesIn -在此简化示例中：

Use testing::ValuesIn - like in this simplified example:

class SomeTests : public TestWithParam<int>
{
public:

};

TEST_P(SomeTests, shouldBePositive)
{
    ASSERT_GT(GetParam(), 0);
}

还有-如何从输入流中获取值的方法：

And - the way how to get values from input stream:

std::ifstream inputValuesFromFile("input.txt");
INSTANTIATE_TEST_CASE_P(FromFileStream,
                        SomeTests,
                        ValuesIn(std::istream_iterator<int>(inputValuesFromFile), 
                                 std::istream_iterator<int>()));

要使用比 int更复杂的类型，您需要为其编写一个运算符>>-例如：

To use more complicated types than "int" you need to write an operator >> for it - like:

struct A
{
    int a;
    std::vector<int> b;
}
std::istream& operator >> (std::istream& is, A& out)
{
     std::size_t bSize;
     if ((is >> A.a) && (is >> bSize))
     {
         out.b.reserve(bSize);
         while (bSize-- > 0)
         {
             int b;
             if (!(is >> b))
                break;
             out.b.push_back(b);   
         }
     }
     return is;
}

当然-在更复杂的情况下-考虑使用类似XMl的（json ？）格式和比 std :: istream_iterator< T> 更专业的迭代器。

Of course - in more complicated cases - consider to use XMl-like (json?) formats and some more specialized iterators than std::istream_iterator<T>.

对于XML-像格式-您可以考虑采用这种方案（这是非常假设的代码-我脑海中没有任何此类库）：

For XML - like formats - you might consider such scheme (this is very hypothetical code - I do not have any such library in my mind):

SomeLib::File xmlData("input.xml");

class S1BasedTests : public TestWithParam<S1>
{};

TEST_P(S1BasedTests , shouldXxxx)
{
    const S1& s1 = GetParam();
    ...
}
auto s1Entities = file.filterBy<S1>("S1");
INSTANTIATE_TEST_CASE_P(S1,
                        S1BasedTests,
                        ValuesIn(s1Entities.begin(), s1Entities .end()));

//等对于您想要的任何S1类型

// etc for any types S1 you want

如果市场上没有这样的C ++类型友好库（我搜索了2分钟却没有找到）-那么可能是这样的：

If there is no such C++-type-friendly library on the market (I searched for 2 minutes and did not find) - then maybe something like this:

SomeLib::File xmlFile("input.xml");

struct S1BasedTests : public TestWithParam<SomeLib::Node*>
{
   struct S1 // xml=<S1 a="1" b="2"/>
   {
       int a;
       int b;
   };
   S1 readNode()
   {
        S1 s1{};
        s1.a = GetParam()->getNode("a").getValue<int>();
        s1.b = GetParam()->getNode("b").getValue<float>();
        return s1;
   }
};

TEST_P(S1BasedTests , shouldXxxx)
{
    const S1& s1 = readNode();
    ...
}
INSTANTIATE_TEST_CASE_P(S1,
                        S1BasedTests ,
                        ValuesIn(xmlFile.getNode("S1").getChildren()));
                        // xml=<S1s> <S1.../> <S1.../> </S1>

//等对于任何节点类型，例如S1

// etc for any node types like S1

这篇关于数据驱动的单元测试与Google Test的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！