List implementation in C

list.c

#include "testlib.h"
#include <stdlib.h>
#include <stddef.h>
#include <inttypes.h>

typedef struct vec {
  void **data;
  uint32_t len;
  uint32_t cap;
} vec;

vec *vec_new() {
  vec *v = (vec *) malloc(sizeof(vec));
  v->data = NULL;
  v->len = 0;
  v->cap = 0;
  return v;
}

void vec_grow(vec *v) {
  if (v->cap == 0) {
    // i dont care about errors here
    v->data = malloc(sizeof( void* ));
    v->cap = 1;
  } else {
    v->cap = v->cap * 2;
    // i dont care about errors here
    v->data = realloc(v->data, v->cap * sizeof(void *));
  }
}

void vec_push(vec *v, void *data) {
  if (v->len == v->cap) {
    vec_grow(v);
  }

  v->data[v->len] = data;

  v->len += 1;
}

void *vec_pop(vec *v) {
  if (v->len == 0) {
    return NULL;
  }

  v->len -= 1;
  return v->data[v->len];
}

void vec_free(vec *v) {
  free(v->data);
  free(v);
}

int main() {
  test_start("vec");
  vec *v = vec_new();

  test_equals_int(0, v->len, "len has to be zero");

  int elem = 5;
  vec_push(v, &elem);
  test_equals_int(1, v->len, "len has to be one");

  test_equals_int(elem, *(int *)vec_pop(v), "elem must match");

  vec_push(v, &elem);
  vec_push(v, &elem);
  vec_push(v, &elem);
  vec_push(v, &elem);
  vec_push(v, &elem);
  vec_push(v, &elem);

  test_equals_int(6, v->len, "len has to be 6");

  vec_free(v);
}