minunit.h

#ifndef __MINUNIT_H__
#define __MINUNIT_H__

#define mu_assert(message, test) do { if (!(test)) return message; } while (0)
#define mu_run_test(test) do { char *message = test(); tests_run++; \
  if (message) return message; } while (0)
extern int tests_run;

#endif //__MINUNIT_H__

test.c

#include "minunit.h"

static char * test_something() {
  mu_assert("should have something true, or this prints!", 3 == 3);
  return 0;
}

static char * all_tests() {
  mu_run_test(test_something);
  return 0;
}

int main(int argc, char **argv) {
  char *result = all_tests();
  if (result != 0) {
    printf("%s\n", result);
  }
  else {
    printf("ALL TESTS PASSED\n");
  }
  printf("Tests run: %d\n", tests_run);

  return result != 0;
}