GTest C对main进行多重定义

Question

我正在尝试学习如何使用gtest在c++中创建单元测试。我写了一个简单的库来测试，在那里我创建了一个阶乘函数

src/main.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;
}

src/main.h

#ifndef GTEST_LEARN_MAIN_H
#define GTEST_LEARN_MAIN_H
int factorial(int n);
#endif //GTEST_LEARN_MAIN_H

src/CMakeLists.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，在这里我测试阶乘函数

test/main.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();
}

根据github页面上的文档，我将gtest添加到了我的项目中

中的test/CMakeLists.txt

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      ""
)

test/CMakeLists.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，说multiple definition of 'main'。它还说main的第一个定义是在test/main.cpp中，但在我将main函数添加到该文件中之前，它说main首先在googletest-src/googletest/src/gtest_main.cc中声明，即gtest库。对于这个项目，我可以从src/main中删除main，因为它没有任何用途，但在实际应用程序中，这不是一个选项。我想我必须做一些CMake配置来忽略gtest main或类似的东西，但我不知道怎么做。有人能帮我吗？提前感谢！

这是我的项目级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

您声明了两个主要函数，我所做的是：

#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

对于测试编译，我声明了一个TESTING宏，然后确保编译器只看到一个主函数。对于编译应用程序，它看不到测试主体。