не находит gmock

При сборке появлется ошибка - хотя по указанным путям данные файлы существуют. Ошибка:

CMakeFiles/u_tests.dir/backend/testBackend.cpp.o: In function `testing::internal::Assert(bool, char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
/usr/include/gmock/internal/gmock-internal-utils.h:284: undefined reference to `testing::internal::GetFailureReporter()'
CMakeFiles/u_tests.dir/backend/testBackend.cpp.o: In function `testing::internal::ExpectationBase::is_retired() const':
/usr/include/gmock/gmock-spec-builders.h:774: undefined reference to `testing::internal::g_gmock_mutex'
CMakeFiles/u_tests.dir/backend/testBackend.cpp.o: In function `testing::internal::ExpectationBase::Retire()':
/usr/include/gmock/gmock-spec-builders.h:781: undefined reference to `testing::internal::g_gmock_mutex'
CMakeFiles/u_tests.dir/backend/testBackend.cpp.o: In function `testing::internal::ExpectationBase::IsSaturated() const':
/usr/include/gmock/gmock-spec-builders.h:795: undefined reference to `testing::internal::g_gmock_mutex'

часть cmake:

target_link_libraries(${UT_NAME}
    PUBLIC
        ${CMAKE_THREAD_LIBS_INIT}

        pthread
        gtest
        GTest::GTest 
        GTest::Main
)

часть Mock-класс

class FrontendMock : public IConnection { public:
    MOCK_METHOD0(start, void(void));
    MOCK_METHOD0(async_read_pb_header, void(void));
    MOCK_METHOD2(do_parse_pb_header, void(boost::system::error_code, std::size_t)); };