index.test.js

const { BinarySearchTree } = require('./');

describe('BinarySearchTree#BFS', () => {
  const bstOne = new BinarySearchTree();
  const bstTwo = new BinarySearchTree();
  const bstThree = new BinarySearchTree();

  beforeAll(() => {
    const newNodesbstOne = [50, 45, 65, 35, 25, 20, 75, 60, 85, 47, 37, 27];
    newNodesbstOne.forEach(val => bstOne.insert(val));

    const newNodebstTwo = [41, 20, 65, 29, 11, 91, 50, 99, 72, 100];
    newNodebstTwo.forEach(val => bstTwo.insert(val));
  });

  it('should return an array', () => {
    expect(Array.isArray(bstOne.bfs())).toBe(true);
    expect(Array.isArray(bstTwo.bfs())).toBe(true);
    expect(Array.isArray(bstThree.bfs())).toBe(true);
  });

  it('should return an array with the following order', () => {
    expect(bstOne.bfs()).toEqual([50, 45, 65, 35, 47, 60, 75, 25, 37, 85, 20, 27]);
    expect(bstTwo.bfs()).toEqual([41, 20, 65, 11, 29, 50, 91, 72, 99, 100]);
    expect(bstThree.bfs()).toEqual([]);
  });
});