test: added test for remove at

src/arraylist.c

@@ -262,7 +262,7 @@ ArrayListErr arraylist_pop_front(ArrayList *arr, void *out) {
     memmove(
         arr->buffer,
         arr->buffer + arr->elem_size,
-        arr->len * arr->elem_size);
+        (arr->len - 1) * arr->elem_size);
 
     arr->len--;
 
@@ -290,13 +290,10 @@ ArrayListErr arraylist_remove_at(ArrayList *arr, size_t index, void *out) {
         );
     }
 
-    for (size_t i = index; i < arr->len; i++) {
-        memcpy(
-            arr->buffer + (index * arr->elem_size),
-            arr->buffer + ((i + 1) * arr->elem_size),
-            arr->elem_size
-        );
-    }
+    memmove(
+        arr->buffer + (index * arr->elem_size),
+        arr->buffer + ((index + 1) * arr->elem_size),
+        (arr->len - index) * arr->elem_size);
 
     arr->len--;