Gtest: Undefined References

问题:

I am trying to use GoogleTest to test a simple function, but as I run make in my build folder, the compiler throws Undefined Reference error messages at me. I've referenced the gtest header file, so I'm not sure what is wrong. Any ideas? I'm new to the entire subject of both unix and unit testing , so I could very well be missing something simple. Thanks in advance!

Error Messages:

CMakeFiles/Proj2.dir/main.cpp.o: In function `main':
main.cpp:(.text+0x1e): undefined reference to `testing::InitGoogleTest(int*, char**)'
main.cpp:(.text+0x23): undefined reference to `testing::UnitTest::GetInstance()'
main.cpp:(.text+0x2b): undefined reference to `testing::UnitTest::Run()'
collect2: error: ld returned 1 exit status

main.cpp

#include "gtest/gtest.h"

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

Test.cpp

#include "gtest/gtest.h"
#include "Testable.h"

TEST(GetTwoTest, Two) {
    EXPECT_EQ(2, GetTwo());
}

Testable.cpp

#include "Testable.h"

int GetTwo() {
    return 3;
}

Here is my CMakeLists.txt file:

cmake_minimum_required(VERSION 2.6)

SET(CMAKE_CXX_FLAGS "-std=gnu++11") #Turn on C++11 Support

set(FILES_TO_TEST Testable.cpp)
set(UNIT_TESTS Test.cpp)
set(MAIN_FILE main.cpp)

add_subdirectory(gtest) #Build all the gtest stuff
include_directories(gtest/include)
include_directories(.)
add_library(codeToTest ${FILES_TO_TEST})

add_executable(Proj2 ${MAIN_FILE})
target_link_libraries(Proj2 codeToTest)

add_executable(unit-test ${UNIT_TESTS})
target_link_libraries(unit-test gtest gtest_main rt pthread codeToTest)

回答1:

Your setup looks to be almost correct. However, you're needing to have 2 separate main functions; one for the real executable Proj2 and another with the gtest includes and functions for the test executable unit-test.

You could do this by having 2 different main.cpp files, say main.cpp and test_main.cpp. The one you've shown would be test_main.cpp, and would be included in the add_executable(unit-test ... command.

Your new main.cpp would have no references to gtest, either includes or functions.

回答2:

From linker errors it is obvious that you did not link gtest library to your test program.

See Primer:

To write a test program using Google Test, you need to compile Google Test into a library and link your test with it. ...

Just see this doc for details about your compiler and system.