Pre-compiling googletest to run on baremetal - cmake

Question

I've been trying to use google test on bare metal and followed the slightly harder variant of the website below to precompile google test, obtain the library file and then link it in a project's CMake
https://clarkli86.wordpress.com/2016/01/28/build-googletest-for-baremetal-targets-stm32/
The CMake runs smoothly throughout the project, in which I'm trying to integrate google test, up to the part it starts building google test
The CMakeLists file of the folder containing the tests and google test looks like this:
set(BINARY ${CMAKE_PROJECT_NAME}_tst)
set(SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp)
#add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/googletest/)
add_executable(${BINARY} ${SOURCE})
add_test(NAME ${BINARY} COMMAND ${BINARY})
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/googletest/googletest/include/gtest)
link_directories(${CMAKE_CURRENT_SOURCE_DIR}/googletest/googletest/include/gtest)
target_link_libraries(${BINARY} PUBLIC Library gtest)
which gives the following error:
SDK_test/testing/main.cpp:3:25: fatal error: gtest/gtest.h: No such file or directory
compilation terminated.
make[2]: *** [testing/CMakeFiles/SdkTest_tst.dir/build.make:63: testing/CMakeFiles/SdkTest_tst.dir/main.cpp.obj] Error 1
make[1]: *** [CMakeFiles/Makefile2:9691: testing/CMakeFiles/SdkTest_tst.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
On the main.cpp file, gtest is called using:
#include <gtest/gtest.h>
I've tried to build the project using this flag:
-l/testing/googletest/googletest/include/gtest
include the path directly in the CMakeLists, and all result in the error above
If I uncomment the add_subdirectory line, the make build fails due to the pthreads and sleep libraries
examples:
testing/googletest/googletest/include/gtest/internal/gtest-port.h:1453:24: error: 'nanosleep' was not declared in this scope
nanosleep(&time, NULL);
testing/googletest/googletest/include/gtest/internal/gtest-port.h:1499:3: error: 'pthread_mutex_t' does not name a type
pthread_mutex_t mutex_;
Any suggestions on how to properly link the library?