const compare = require('../src/compare');

describe('compare function', () => {
  test('returns empty array when all objects are equal', () => {
    const a = { x: 1, y: 2 };
    const b = { x: 1, y: 2 };
    const c = { x: 1, y: 2 };
    expect(compare(a, b, c)).toEqual([]);
  });

  test('detects differences in top-level keys', () => {
    const a = { x: 1, y: 2 };
    const b = { x: 1, y: 3 };
    const c = { x: 1, y: 2 };
    expect(compare(a, b, c)).toEqual([
      { key: 'y', values: [2, 3, 2] },
    ]);
  });

  test('detects differences in nested objects', () => {
    const a = { a: { b: 1 } };
    const b = { a: { b: 2 } };
    const c = { a: { b: 1 } };
    expect(compare(a, b, c)).toEqual([
      { key: 'a.b', values: [1, 2, 1] },
    ]);
  });

  test('handles missing keys', () => {
    const a = { x: 1 };
    const b = { x: 1, y: 2 };
    const c = { x: 1 };
    expect(compare(a, b, c)).toEqual([
      { key: 'y', values: [undefined, 2, undefined] },
    ]);
  });
});