// Copyright 2018-2026 the Deno authors. MIT license.
import { assert, assertEquals } from "@std/assert";
import { copy } from "./copy.ts";

Deno.test("copy()", function () {
  const dst = new Uint8Array(4);

  dst.fill(0);
  let src = Uint8Array.of(1, 2);
  let len = copy(src, dst, 0);
  assert(len === 2);
  assertEquals(dst, Uint8Array.of(1, 2, 0, 0));

  dst.fill(0);
  src = Uint8Array.of(1, 2);
  len = copy(src, dst, 1);
  assert(len === 2);
  assertEquals(dst, Uint8Array.of(0, 1, 2, 0));

  dst.fill(0);
  src = Uint8Array.of(1, 2, 3, 4, 5);
  len = copy(src, dst);
  assert(len === 4);
  assertEquals(dst, Uint8Array.of(1, 2, 3, 4));

  dst.fill(0);
  src = Uint8Array.of(1, 2);
  len = copy(src, dst, 100);
  assert(len === 0);
  assertEquals(dst, Uint8Array.of(0, 0, 0, 0));

  dst.fill(0);
  src = Uint8Array.of(3, 4);
  len = copy(src, dst, -2);
  assert(len === 2);
  assertEquals(dst, Uint8Array.of(3, 4, 0, 0));
});
