GTest CMake 多重定义的main

Question

我正在努力学习如何使用 gtest 用于在c++中创建单元测试。我写了一个简单的库来测试，在这里我创建了一个因子函数

srcmain.cpp

#include <iostream>

int factorial(int n) {
    if (n == 1)
        return 1;
    return n * factorial(n - 1);
}


// Default main function
int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

srcmain.h

#ifndef GTEST_LEARN_MAIN_H
#define GTEST_LEARN_MAIN_H

int factorial(int n);

#endif //GTEST_LEARN_MAIN_H

srcCMakeLists.txt

add_executable(gtest_learn main.cpp main.h)
add_library(factorial_lib STATIC main.cpp main.h)

然后我创建了一个单元测试，在这里我测试因子函数

testmain.cpp

#include "main.h"
#include "gtest/gtest.h"


TEST(MyTestSuite,MyTest){
    EXPECT_EQ(factorial(4),24);
}


int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}

我在我的项目中添加了gtest，按照在 github 网页

testCMakeLists.txt.in

cmake_minimum_required(VERSION 2.8.2)

project(googletest-download NONE)

include(ExternalProject)
ExternalProject_Add(googletest
  GIT_REPOSITORY    https://github.com/google/googletest.git
  GIT_TAG           master
  SOURCE_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-src"
  BINARY_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-build"
  CONFIGURE_COMMAND ""
  BUILD_COMMAND     ""
  INSTALL_COMMAND   ""
  TEST_COMMAND      ""
)

testCMakeLists.txt

cmake_minimum_required(VERSION 3.15)
project(tests)

# Download and unpack googletest at configure time
configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt)
execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
        RESULT_VARIABLE result
        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download )
if(result)
    message(FATAL_ERROR "CMake step for googletest failed: ${result}")
endif()
execute_process(COMMAND ${CMAKE_COMMAND} --build .
        RESULT_VARIABLE result
        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download )
if(result)
    message(FATAL_ERROR "Build step for googletest failed: ${result}")
endif()

# Prevent overriding the parent project's compiler/linker
# settings on Windows
set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)

# Add googletest directly to our build. This defines
# the gtest and gtest_main targets.
add_subdirectory(${CMAKE_CURRENT_BINARY_DIR}/googletest-src
        ${CMAKE_CURRENT_BINARY_DIR}/googletest-build
        EXCLUDE_FROM_ALL)

# The gtest/gtest_main targets carry header search path
# dependencies automatically when using CMake 2.8.11 or
# later. Otherwise we have to add them here ourselves.
if (CMAKE_VERSION VERSION_LESS 2.8.11)
    include_directories("${gtest_SOURCE_DIR}/include")
endif()

add_executable(tests main.cpp)
target_link_libraries(tests gtest_main)
target_link_libraries(tests factorial_lib)
add_test(NAME example_test COMMAND tests)

当我试图运行我的测试时，我得到一个错误信息说 multiple definition of 'main'. 它还说，main的第一个定义是在。test/main.cpp但在我在这个文件中添加主函数之前，它说 main 首次宣布于 googletest-src/googletest/src/gtest_main.cc，即 gtest 库。在这个项目中，我可以删除 main 从 src/main 因为它没有任何作用，但在真实的应用中，这不是一个选项。我想我必须做一些CMake配置来忽略gtest主程序或类似的东西，但我不知道怎么做。谁能帮帮我？先谢谢你

以下是我的项目级CMakeLists

cmake_minimum_required(VERSION 3.15)
project(gtest_learn)

set(CMAKE_CXX_STANDARD 14)


include_directories(src)

add_subdirectory(src)
add_subdirectory(test)

Answer 1

你声明了两个主函数，我的做法是。

#ifndef TESTING
// Default main function
int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}
#endif

#ifdef TESTING
int main(int argc, char **argv) {
    ::testing::InitGoogleTest(&argc, argv);
    return RUN_ALL_TESTS();
}
#endif

为了测试编译，我声明了一个TESTING宏，它确保编译器只看到一个主函数。对于编译程序，它不会看到测试主函数。