How the use unit test in cmake in language C?

I have a C project:

.
├── build
├── bin
│   └── parser
├── CMakeLists.txt
├── configure.h.in

├── inc
│   ├── configure.h
│   ├── diam_dict.h
│   └── unit_tests.h
├── README.txt
├── src
│   └── diam_dict.c
└── testing
    └── unit_tests.c

I want to put unit tests in the directory "testing", in the file "unit_tests.c".
I want to test all the functions of the file "src/diam_dict.c", what should I do to let "unit_tests.c" know where are the functions to test?
[what should I write in the file "unit_tests.c" and the top level cmake file "CMakeLists.txt"?]
(I should call all the functions of the source code file "diam_dict.c" to test them)


ps: The header file "diam_dict.h" contains all the prototypes of the functions in the source file "diam_dict.c", and the header file "unit_tests.h" cotains all the prototypes of the test file "unit_tests.c".