text: import { assert } from 'chai';
  import { serializeUndirectedGraph, deserializeUndirectedGraph } from 'utils/graph-util';
  import alienOrder from '../alien-dictionary';
  
  describe('Alien Dictionary', () => {
    const testCases = [
      ['', ''],
      [null, ''],
      [['zoro'], 'zoro'],
      [['wrt', 'wrf', 'er', 'ett', 'rftt'], 'wertf'],
      [['z', 'x'], 'zx'],
      [['z', 'x', 'z'], ''],
    ];
  
    testCases.forEach((testCase, index) => {
      it(`should get the alien dictionary ${index}`, () => {
        const words = testCase[0];
        const expected = testCase[1];
        const actual = alienOrder(words);
        assert.equal(actual, expected);
      });
    });
  });
  