feat(hmpl): render simple placeholder with memory leak of course

package/c/chectic/test/arena.c

@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "chectic.h"
+
+void test_arena_init() {
+  Arena arena = arena_init(128);
+  assert(arena.begin != NULL);
+  assert(arena.current == arena.begin);
+  assert(arena.capacity == 128);
+  arena_free(&arena);
+}
+
+void test_arena_alloc() {
+  Arena arena = arena_init(64);
+  void *ptr1 = arena_alloc(&arena, 16);
+  assert(ptr1 != NULL);
+  void *ptr2 = arena_alloc(&arena, 16);
+  assert(ptr2 != NULL);
+  raise_debug("%d - %d = %d", (size_t)ptr2, (size_t)ptr1, (char *)ptr2 - (char *)ptr1);
+  assert((char *)ptr2 - (char *)ptr1 == 16);
+  arena_free(&arena);
+}
+
+void test_arena_alloc_or_null_out_of_memory() {
+  Arena arena = arena_init(32);
+  void *ptr = arena_alloc_or_null(&arena, 64);
+  raise_debug("%d %d %d %d", arena.begin, arena.current, arena.capacity, (size_t)ptr);
+  assert(ptr == NULL);
+  arena_free(&arena);
+}
+
+void test_arena_reset() {
+  Arena arena = arena_init(64);
+  void *ptr1 = arena_alloc(&arena, 16);
+  arena_reset(&arena);
+  void *ptr2 = arena_alloc(&arena, 16);
+  assert(ptr1 == ptr2); // same address after reset
+  arena_free(&arena);
+}
+
+void test_arena_null_init() {
+  Arena arena = {0};
+  void *ptr = arena_alloc_or_null(&arena, 32);
+  assert(ptr != NULL);
+  arena_free(&arena);
+}
+
+int main() {
+  set_output_color_mode(COLOR_MODE_DISABLE);
+  logger_level(LOG_LEVEL_DEBUG);                                                            \
+
+  test_arena_init();
+  test_arena_alloc();
+  test_arena_alloc_or_null_out_of_memory();
+  test_arena_reset();
+  test_arena_null_init();
+  printf("All tests passed.\n");
+}