import { describe, expect, it } from 'vitest';

import { resolveExclusiveVisibleChildId } from '../src/view/ui-editor/components/preview/exclusiveVisibility';

describe('resolveExclusiveVisibleChildId', () => {
  const children = [{ id: 'first' }, { id: 'second' }];

  it('defaults to the first child on initial load', () => {
    expect(resolveExclusiveVisibleChildId(children, new Set())).toBe('first');
  });

  it('uses the first non-hidden child as the explicit selection', () => {
    expect(resolveExclusiveVisibleChildId(children, new Set(['first']))).toBe(
      'second',
    );
  });

  it('keeps every child hidden after a manual hide-all action', () => {
    expect(
      resolveExclusiveVisibleChildId(children, new Set(['first', 'second'])),
    ).toBeNull();
  });

  it('returns null for an empty exclusive container', () => {
    expect(resolveExclusiveVisibleChildId([], new Set())).toBeNull();
  });
});