text: const assert = require('assert');
  
  const db = require('../db');
  const Book = require('../models/book');
  
  const book = new Book({
    name: 'scip',
    author: 'H.A',
    owner: 'ssx',
    description: 'sfasfdfafdfsfafdafd',
    where: 'home',
  });
  
  Book.deleteMany({ name: book.name }, (err) => {});
  
  book.save((err) => {
    if (err) {
      console.log('ERROR: faided to save date.', err.stack);
    }
  });
  
  Book
    .findOne({ name: 'scip' })
    .exec((err, res) => {
      if (err) {
        console.log('ERROR: failed to query datas.', err.stack);
      }
      console.log(typeof res, typeof book);
      assert(typeof res === typeof book, `res: ${typeof res} != book: ${typeof book}`);
      assert.deepStrictEqual(res, book, `result don't equal to origin data\nresult: ${res}\norigin: ${book}`);
    });
  