import { test } from 'node:test';
import assert from 'node:assert/strict';
import { applyMaskAlpha } from './maskedPreview';

test('applyMaskAlpha keeps slab pixels and clears the background', () => {
  const rgba = new Uint8ClampedArray([
    1, 2, 3, 255,
    4, 5, 6, 255,
    7, 8, 9, 255,
  ]);
  const out = applyMaskAlpha(rgba, new Uint8Array([1, 0]));
  assert.deepEqual([...out], [1, 2, 3, 255, 4, 5, 6, 0, 7, 8, 9, 0]);
  assert.deepEqual([...rgba], [1, 2, 3, 255, 4, 5, 6, 255, 7, 8, 9, 255]);
});