GTest CMake multiple definition of main

问题

I am trying to learn how to use gtest for creating unit testing in c++. I wrote a simple library to test, where I created a factorial function

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)

Then I created a unit test where I am testing the factorial function

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();
}

I added gtest to my project following the docs on the github page

test/CMakeLists.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      ""
)

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)

When I am trying to run my test, I get an error saying multiple definition of 'main'. It also says the first definition of main was in test/main.cpp, but before I added the main function in this file, it said that main was first declared in googletest-src/googletest/src/gtest_main.cc, which is the gtest library. For this project I could remove the main from src/main since it serves no purpose, but in a real application that wouldn't be an option. I assume I have to make some CMake config to ignore the gtest main or something like that, but I don't know how. Can anyone help me out? Thanks in advance!

Here is my project-level CMakeLists

cmake_minimum_required(VERSION 3.15)
project(gtest_learn)

set(CMAKE_CXX_STANDARD 14)


include_directories(src)

add_subdirectory(src)
add_subdirectory(test)

回答1:

You have two main functions declared, what I do is:

#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

For test compilation I declare a TESTING macro, which then ensures, that the compiler sees only one main function. For compiling the application, it does not see the test main.

来源：https://stackoverflow.com/questions/61609265/gtest-cmake-multiple-definition-of-main

标签

c++

cmake

googletest