How to test with jest ?

I have model method for method of controller. How to test it with jest ? How to create mock of Objection ?

const { Errors } = require('../../db/models/Errors');

module.exports = async function get(page = 0, perPage = 5, errorsFilter = {}) {
  try {
    const query = Errors
      .query()
      .orderBy('id', 'DESC')
      .page(page, perPage);

    // filter

    if (Object.keys(errorsFilter).length) {
      for (let field in errorsFilter) {
        if ( errorsFilter.hasOwnProperty(field) ) {
          if (field === 'dateStart') {
            query.where('date', '>=', `${ errorsFilter[field] }`);
          } else if (field === 'dateEnd') {
            query.where('date', '<=', `${ errorsFilter[field] }`);
          } else {
            query.where(field, 'like', `%${ errorsFilter[field] }%`);
          }
        }
      }
    }
    
    const { results, total } = await query;

    return {
      items:       results,
      itemsOnPage: Number(perPage),
      currentPage: Number(page),
      totalPage:   Math.ceil(total/perPage),
      totalItems:  Number(total)
    }
  } catch (error) {
    // log error -----------------------------------------------------------
    console.log({Error: error});
    // ---------------------------------------------------------------------
  }
};

My test file:

require('dotenv').config();

const express       = require('express');
const request       = require('supertest');
const bodyParser    = require('body-parser');
const { Objection } = require('objection');
const { QueryBuilder } = require('objection');
const { Errors }    = require('../../../../server/db/models/Errors');

const errors      = require('../../../../server/controllers/errors');
const { i18next, i18nextMiddleware } = require('../../../i18n-server');

const builder = QueryBuilder.forClass(Errors);

console.log(builder.resolve);

jest.spyOn(Errors, 'query').mockImplementation(builder.resolve({ type: 'test' }));

const app = express();

app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.use(i18nextMiddleware);

app.get(
  '/',
  errors.getErrors
);

describe('get errors', () => {
  it('success', done => {
    i18next.on('initialized', () => {
      request(app)
        .get('/')
        .query({page: 1, perPage: 5})
        .end((err, res) => {
          if (err) return done(err);

          expect(res.status).toBe(200);

          done();
        });
    })
  });
});

I have error: TypeError: specificMockImpl.apply is not a function

[fiznool]

I’m not sure if you should really be mocking out the database. I would consider any test that runs against Objection models to be an integration test, which should be backed by a real database.

If you really want to mock out the response, you could look at the resolve and reject Query Builder methods, although I’m unsure whether you can skip a database connection if using these.

As an aside, you might have more luck posting this sort of question on the gitter channel.

[otaviosoares]

I created this function, see if it helps

import { QueryBuilder } from 'objection'
export default function mockmodel(Model) {
  const query = QueryBuilder.forClass(Model)
  jest.spyOn(Model, 'query').mockReturnValue(query)
  return query
}

const body = { test : 1 }
const queryBuilderMock = mockModel(YourModel).resolve(body)
YourModel.query.insert({})
// if needed
const insertMock = jest.spyOn(queryBuilderMock, 'insert')
expect(insertMock).toHaveBeenCalledTimes(1)