Adding tests [ server tests ] for the project

The test library I am planning to use is jest. category of tests :

• API tests
• Snapshot tests

For now just two, please add more if works fine

Example of a test in chai

describe('/GET /', () => {
    it('it should GET all the books', (done) => {
      chai.request(server)
          .get('/')
          .end((err, res) => {
                res.should.have.status(200);
            done();
          });
    });
});

Thanks