import { describe, it, expect } from 'vitest';
import { groupObjectsByFirstLetter } from '../group-objects-by-first-letter';

describe('groupObjectsByFirstLetter', () => {
  const items = [
    { name: 'Alice' },
    { name: 'Anna' },
    { name: 'Bob' },
    { name: '123test' },
  ];

  it('группирует по первой букве', () => {
    const result = groupObjectsByFirstLetter(items, 'name');
    expect(result['A']).toHaveLength(2);
    expect(result['B']).toHaveLength(1);
  });

  it('цифры попадают в POST', () => {
    const result = groupObjectsByFirstLetter(items, 'name');
    expect(result['POST']).toHaveLength(1);
    expect(result['POST'][0]).toEqual({ name: '123test' });
  });

  it('кастомный nonLetterKey', () => {
    const result = groupObjectsByFirstLetter(items, 'name', 'OTHER');
    expect(result['OTHER']).toHaveLength(1);
  });

  it('пустой массив', () => {
    const result = groupObjectsByFirstLetter([], 'name');
    expect(result).toEqual({});
  });
});