CMake cannot find GoogleTest required library in Ubuntu

Question

Similar issue here.

This is my CMakeLists.txt:

cmake_minimum_required(VERSION 2.6)

# Locate GTest
find_package(GTest REQUIRED)
include_directories(${GTEST_INCLUDE_DIRS})

# Add test cpp file
add_executable(foo foo.cpp)

# Link test executable against gtest & gtest_main
target_link_libraries(foo ${GTEST_LIBRARIES} ${GTEST_MAIN_LIBRARIES} pthread)

And my foo.cpp:

#include <gtest/gtest.h>

TEST(sample_test_case, sample_test)
{
    EXPECT_EQ(1, 1);
}

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

Now, all works fine when using the g++ compiler. However, when attempting to use QNX's compiler, ntox86-c++, I run into this problem:

CMake Error at /usr/share/cmake-2.8/Modules/FindPackageHandleStandardArgs.cmake:97 (MESSAGE): Could NOT find GTest (missing: GTEST_LIBRARY GTEST_INCLUDE_DIR GTEST_MAIN_LIBRARY)

I am on Ubuntu using the ntox86-c++ compiler, googletest, and cmake-gui.

What gives?

Solution 1

Google test was probably not properly installed (libgtest-dev may install only source files that needed to be compiled). I had the same problem and I followed the instructions from http://www.eriksmistad.no/getting-started-with-google-test-on-ubuntu/

sudo apt-get install libgtest-dev
sudo apt-get install cmake # install cmake
cd /usr/src/gtest
sudo cmake CMakeLists.txt
sudo make

#copy or symlink libgtest.a and libgtest_main.a to your /usr/lib folder
sudo cp *.a /usr/lib

This worked for me.

Solution 2

As explained by @detrick, the Ubuntu package libgtest-dev only installs sources, so you need to build and install the libraries yourself.

However, there is a much simpler way for building and installing since Ubuntu 18.04 than the manual commands in other answers:

sudo apt install libgtest-dev build-essential cmake
cd /usr/src/googletest
sudo cmake .
sudo cmake --build . --target install

Solution 3

ntox86-c++ looks like a cross-compiler, libgtest-dev package does not provide compiled library for the target platform (QNX).

Since year 2014 compiled libraries was dropped from libgtest-dev and has been added again in Ubuntu-20.04 focal, so find_package(GTest REQUIRED) does not work on Ubuntu-16.04 xenial and Ubuntu-18.04 bionic. The reason is given in /usr/share/doc/googletest/README.Debian (/usr/share/doc/libgtest-dev/README.Debian) and in e.g. in /usr/src/googletest/googletest/docs/V1_7_FAQ.md "Why is it not recommended to install a pre-compiled copy of Google Test (for example, into /usr/local)" section. Difference in compiler flags for the library and for a test could generate incompatible executable code. The problem with 18.04 and 16.04 is the reason why I have decided to add another answer to the old question.

add_subdirectory could be used to compile gtest provided by system package

set(GTest_ROOT /usr/src/googletest/googletest)
add_subdirectory(${GTest_ROOT}
        "${CMAKE_CURRENT_BINARY_DIR}/googletest" EXCLUDE_FROM_ALL)

add_executable(test test.cpp)
target_link_libraries(test gtest_main)
# or just gtest if main function is defined

Instead of using system package for googletest sources there are at least 2 variants how to obtain particular version from git (besides obvious submodule), see

• https://cmake.org/cmake/help/latest/module/FetchContent.html
• https://github.com/google/googletest/blob/master/googletest/README.md

Comments

[usr1234567]

You should not copy your library into /usr/lib. Instead pass CMake the right flag like GTEST_ROOT or add your GTest directory into CMake's search path.

[Conchylicultor]

@detrick forgot to add cd /usr/src/gtest before running sudo cmake CMakeLists.txt to compile libgtest-dev

[jcmonteiro]

Note that you should not copy generated files by hand. Instead, use sudo make install

[jinge]

This doesn't work in Ubuntu 16.04. No rule to make target 'install'.

[mrts]

@jinge, you are right, this works for Ubuntu 18.04 and newer. I updated the answer accordingly.