Mbed greentea utest header not found

Hi Sir,

I added a unit test according to:
Greentea testing applications - Tools | Mbed OS 5 Documentation

When I compile the simple test, tests-test-AcmInit-simple-test, the following compilation error happens:

    *[Fatal Error] main.cpp@7,10: 'utest/utest.h' file not found*
  •    [DEBUG] Return: 1*
    
  •    [DEBUG] Output: .\TESTS\test-AcmInit\simple-test\main.cpp:7:10: fatal error: 'utest/utest.h' file not found*
    
  •    [DEBUG] Output: #include "utest/utest.h"*
    
  •    [DEBUG] Output:          ^~~~~~~~~~~~~~~*
    
  •    [DEBUG] Output: 1 error generated.*
    

In my project custom_targets.json, I added “utest” in “requires”.

Can I know how to include folder of “\mbed-os\features\frameworks\unity” properly?

Thanks,
Shoujie