Unit Testing with CMocka

CMocka is a lightweight unit‑testing framework for C.

1. Install via package manager (apt-get install libcmocka-dev).
2. Write test functions returning void.
3. Use assert_int_equal, assert_string_equal, etc.
4. Build with -lcmocka.

#include <stdarg.h>
#include <stddef.h>
#include <setjmp.h>
#include <cmocka.h>

int add(int a, int b) { return a + b; }

static void test_add(void **state) {
    (void) state; // unused
    assert_int_equal(add(2,3), 5);
    assert_int_equal(add(-1,1), 0);
}

int main(void) {
    const struct CMUnitTest tests[] = { cmocka_unit_test(test_add) };
    return cmocka_run_group_tests(tests, NULL, NULL);
}

Run with ./test_add – a pass yields a green OK line.

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📚 Why Unit Test?

• Detect regressions early.
• Document expected behaviour.
• Encourage design with testable functions (small, pure logic).