Google单元测试sample分析（一）

本文开始从googletest提供的sample案例分析如何使用单元测试，

代码路径在googletest/googletest/samples/sample1.unittest.cc
本文件主要介绍EXPECT*相关宏使用

EXPECT_EQ 判断是否相等
EXPECT_TRUE 是否为True
EXPECT_FALSE 是否为False

TEST(FactorialTest, Negative) {// This test is named "Negative", and belongs to the "FactorialTest"// test case.EXPECT_EQ(1, Factorial(-5));EXPECT_EQ(1, Factorial(-1));EXPECT_GT(Factorial(-10), 0);// <TechnicalDetails>//// EXPECT_EQ(expected, actual) is the same as////   EXPECT_TRUE((expected) == (actual))//// except that it will print both the expected value and the actual// value when the assertion fails.  This is very helpful for// debugging.  Therefore in this case EXPECT_EQ is preferred.//// On the other hand, EXPECT_TRUE accepts any Boolean expression,// and is thus more general.//// </TechnicalDetails>
}

下面介绍sample2_unittest.cc文件

这里测试MyString类，
EXPECT_STREQ(nullptr, s.c_string()); //这里的STREQ是判断字符串内容，s为空类比较要使用nullptr

TEST(MyString, DefaultConstructor) {const MyString s;// Asserts that s.c_string() returns NULL.//// <TechnicalDetails>//// If we write NULL instead of////   static_cast<const char *>(NULL)//// in this assertion, it will generate a warning on gcc 3.4.  The// reason is that EXPECT_EQ needs to know the types of its// arguments in order to print them when it fails.  Since NULL is// #defined as 0, the compiler will use the formatter function for// int to print it.  However, gcc thinks that NULL should be used as// a pointer, not an int, and therefore complains.//// The root of the problem is C++'s lack of distinction between the// integer number 0 and the null pointer constant.  Unfortunately,// we have to live with this fact.//// </TechnicalDetails>EXPECT_STREQ(nullptr, s.c_string());EXPECT_EQ(0u, s.Length());
}