C unit test auto-discovery

unit.c

#include <stdbool.h>
#include <stdio.h>

//------------------------------------------------------------------------------
// The code we're testing
int add_one(int x) {
  return x + 1;
}

int multiply(int x, int y) {
  return x * y;
}

//------------------------------------------------------------------------------
// Our little test framework
typedef void (*TestFunctionPtr)(bool *test_passed);

typedef struct TestInfo {
  const char     *name;
  TestFunctionPtr function;
} TestInfo;
typedef const TestInfo* TestInfoPtr;

#define TEST_ASSERT(condition) if (!(condition)) { *test_passed = false; }

#if defined _WIN32
//------------------------------------------------------------------------------
// Windows-specific code

#pragma section("tests$a", read) // for the start symbol
#pragma section("tests$b", read) // for the real TestInfo structures
#pragma section("tests$c", read) // for the stop symbol

__declspec(allocate("tests$a"))
TestInfo __start_test_section;
__declspec(allocate("tests$c"))
TestInfo __stop_test_section;

#define TEST_FUNCTION(name)                                             \
  void test_ ## name(bool *test_passed); /* declaration */              \
  __declspec(allocate("tests$b")) const TestInfo test_info_ ## name = { \
    #name, test_ ## name                                                \
  };                                                                    \
  void test_ ## name(bool *test_passed) /* definition */

#define FIRST_TEST_INFO         (&__start_test_section + 1)
#define ONE_PAST_LAST_TEST_INFO &__stop_test_section

#elif defined __APPLE__
//------------------------------------------------------------------------------
// macOS-specific code

extern TestInfo __start_test_section __asm("section$start$__DATA$test_section");
extern TestInfo __stop_test_section __asm("section$end$__DATA$test_section");

#define FIRST_TEST_INFO         &__start_test_section
#define ONE_PAST_LAST_TEST_INFO &__stop_test_section

#define TEST_FUNCTION(name)                                                              \
  void test_ ## name(bool *test_passed); /* declaration */                               \
  const TestInfo test_info_ ## name __attribute__((section ("__DATA,test_section"))) = { \
    #name, test_ ## name                                                                 \
  };                                                                                     \
  void test_ ## name(bool *test_passed) /* definition */

#elif defined __linux__
//------------------------------------------------------------------------------
// Linux-specific code
extern TestInfo __start_test_section;
extern TestInfo __stop_test_section;

#define FIRST_TEST_INFO         &__start_test_section
#define ONE_PAST_LAST_TEST_INFO &__stop_test_section

#define TEST_FUNCTION(name)                                                       \
  void test_ ## name(bool *test_passed); /* declaration */                        \
  const TestInfo test_info_ ## name __attribute__((section ("test_section"))) = { \
    #name, test_ ## name                                                          \
  };                                                                              \
  void test_ ## name(bool *test_passed) /* definition */

#else
#error Unknown platform!
#endif // End of platform-specific code

//------------------------------------------------------------------------------
// Test functions

TEST_FUNCTION(add_one) {
  TEST_ASSERT(add_one(2) == 3);
  TEST_ASSERT(add_one(-2) == -1);
}

TEST_FUNCTION(multiply) {
  TEST_ASSERT(multiply(3, 5) == 15);
  TEST_ASSERT(multiply(0, 5) == 0);
  TEST_ASSERT(multiply(3, 0) == 0);
  TEST_ASSERT(multiply(12, 12) == 144);
}

//------------------------------------------------------------------------------
// Test runner

void run_all_tests(void) {
  int num_passes   = 0;
  int num_failures = 0;

  for (TestInfo *cur_test = FIRST_TEST_INFO;
                 cur_test < ONE_PAST_LAST_TEST_INFO;
                 cur_test++) {
    printf("Calling test '%s'... ", cur_test->name);
    bool test_passed = true;
    cur_test->function(&test_passed);
    if (test_passed) {
      num_passes++;
      printf("passed\n");
    } else {
      num_failures++;
      printf("FAILED :(\n");
    }
  }
  printf("%d failures, %d passes\n", num_failures, num_passes);
}

int main(void) {
  run_all_tests();
}