如何创建Google test shared library(dll)和static library(lib)，并编写测试用例

1. 从Github下载google test源码
2. 确保本地安装Visual Studio和CMake GUI，本次测试使用VS2017及Cmake GUI 3.20.5
3. 解压googletest-main，打开Cmake GUI，配置源码路径（googletest-main路径），和生成路径（googletest-main/build)，需要在生成路径下创建"build"文件夹，记得检查一下MSVC编译器路径在环境变量目录中
4. 点击"Configure"按钮，在弹出的对话框中，选择"Specify the generator for this project" 为Visual Studio 15 2017编译器，"Option platform for generator(if empty, generator uses: Win32)"为x64，这里生成64位版本库，其他保持默认设置

Selecting Windows SDK version 10.0.17763.0 to target Windows 10.0.19044.
The C compiler identification is MSVC 19.16.27045.0
The CXX compiler identification is MSVC 19.16.27045.0
Detecting C compiler ABI info
Detecting C compiler ABI info - done
Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x64/cl.exe - skipped
Detecting C compile features
Detecting C compile features - done
Detecting CXX compiler ABI info
Detecting CXX compiler ABI info - done
Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x64/cl.exe - skipped
Detecting CXX compile features
Detecting CXX compile features - done
Found Python3: D:/wecode_build_tools/mingw/bin/python3.8.exe (found version "3.8.2") found components: Interpreter 
Looking for pthread.h
Looking for pthread.h - not found
Found Threads: TRUE  
Configuring done

配置完毕后，在Configure上的选择框中，勾选"Build_SHRAED_LIBS"，点击Configure按钮旁边的"Generate"按钮

Selecting Windows SDK version 10.0.17763.0 to target Windows 10.0.19044.
Configuring done
Generating done

生成完毕后，点击"Generate"按钮旁边的"Open Project"按钮，打开VS build项目，选择"Release"/“x64"进行ALL_BUILD”，生成完毕后，在“\googletest-main\build\bin\Release”目录下就会生成dll，在“、googletest-main\build\lib\Release”目录下生成lib，有了这些库，就可以创建GTest测试用例了，通常只需要"gtest/gtest_main"及"gmock/gmock_main"这4个dll/lib文件即可。

5. 创建GTest测试用例：本次测试使用Visual Studio，使用CMake配合MinGW类型，只需要额外创建一个CMakeLists.txt即可。
   创建一个VS console app程序，将googletest-main\include\gtest目录拷贝至项目目录下，添加到项目include path，拷贝gtest/gtest_main lib到项目目录下，添加到项目link目录和项；编写func.h/func.cpp作为待测试API，编写func_test.cpp作为单元测试，编写main程序如下：
   main.cpp

#include "googletest/inc/gtest/gtest.h"

int main()
{
    std::cout << "Hello GTest!\n";

    ::testing::InitGoogleTest();
    return RUN_ALL_TESTS();
}

func_test.cpp

#include "googletest/inc/gtest/gtest.h"
#include "func.h"

TEST(func, add_test) {
    int a = 1, b = 2;
    int c = 3;
    ASSERT_EQ(c, add(a, b));
}

func.h

int add(int a, int b);

func.cpp

#include "func.h"

int add(int a, int b) {
    return a + b;
}

编译后，将gtest/gtest_main dll放在exe生成目录下，运行：

Hello GTest!
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from func
[ RUN      ] func.add_test
[       OK ] func.add_test (4607 ms)
[----------] 1 test from func (4608 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (4609 ms total)
[  PASSED  ] 1 test.

可以为不同的代码模块创建不同的测试用例，放在独立的test.cpp文件中，所有的用例都会执行。