Cmake can't find compiler without editing PATH - c++

Question

so what i am doing is that i am having 2 targets in a project, one is program for embedded device that i am crosscompiling, and the second are tests. I need to build them with 2 different compilers.
To main project i am passing arm compiler path by file toolchain.cmake and its working fine.
But right now i would like to build also the tests without having to add path to mingw64/bin to my environment variables (yes its working if i do that).
Test project is added as:
ExternalProject_Add(${UNIT_TEST_TARGET}
SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/test/
PREFIX ${UNIT_TEST_TARGET}
CMAKE_ARGS ${GTEST_ARGS}
BUILD_ALWAYS TRUE
INSTALL_COMMAND cmake -E echo "Skipping install step."
EXCLUDE_FROM_ALL TRUE)
So right now i would like to pass to this external project file toolchaintests.cmake which looks like :
set(CMAKE_C_COMPILER <my_path_here>/mingw64/bin/gcc.exe)
set(CMAKE_CXX_COMPILER <my_path_here>/mingw64/bin/g++.exe)
with:
list(APPEND GTEST_ARGS "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_CURRENT_SOURCE_DIR}/cmake/toolchaintests.cmake")
and if i do this cmake can't recognize the compilers:
-- The C compiler identification is unknown
-- The CXX compiler identification is unknown
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Check for working C compiler: <my_path_here>/mingw64/bin/gcc.exe
-- Check for working C compiler: <my_path_here>/mingw64/bin/gcc.exe - broken
CMake Error at C:/Program Files/CMake/share/cmake-3.24/Modules/CMakeTestCCompiler.cmake:69 (message):
The C compiler
" <my_path_here>/mingw64/bin/gcc.exe"
is not able to compile a simple test program.
It fails with the following output:
Change Dir: <my_path_here>/out/build/tests/src/tests-build/CMakeFiles/CMakeTmp
Run Build Command(s):C:/Ninja/ninja-win/ninja.exe cmTC_a1c48 && [1/2] Building C object CMakeFiles\cmTC_a1c48.dir\testCCompiler.c.obj
FAILED: CMakeFiles/cmTC_a1c48.dir/testCCompiler.c.obj
<my_path_here>\mingw64\bin\gcc.exe -o CMakeFiles\cmTC_a1c48.dir\testCCompiler.c.obj -c <my_path_here>\out\build\tests\src\tests-build\CMakeFiles\CMakeTmp\testCCompiler.c
ninja: build stopped: subcommand failed.
Can i do this somehow else?