A minimal C unit testing framework (only 3 LOC)

  #include <stdio.h>
  #define test(expr) do {                              \
          if (!(expr)) printf("FAILED: %s\n", #expr);  \
          else printf("    ok: %s\n", #expr);          \
      } while (0)
  
  int main(void) {
      int a = 1;
      test(a == 1);
      test(a == 0);
      return 0;
  }

For those of you working in embedded environments where even that is too heavy: cross-compile or write that stupid macro yourself (it's 3 lines for pity's sake!).

#define mu_run_test(test) do { char message = test(); tests_run++; if (message) return message; } while (0)

Isn't one line but

  #define mu_run_test(test) do { 
  char *message = test();
  tests_run++; 
  if (message) 
    return message; 
  } while (0