Add Test Cases

[sylver2211]

Tutorials: https://developers.sap.com/tutorials/add-test-cases.html

Write here how you think we can improve the tutorial ...

my test failed:

const cds = require('@sap/cds/lib')
const { default: axios } = require('axios')
const { GET, POST, DELETE, PATCH, expect } = cds.test(__dirname + '../../')

the fix was:
const cds = require('@sap/cds/lib')
const { GET, POST, DELETE, PATCH, axios, expect } = cds.test(__dirname + '../../')

and also I had some more incidents and users which. I had to adjust
line 12 expect(await SELECT.from(Incidents)).to.have.length(5) and
line 18 expect(await SELECT.from(Customers)).to.have.length(4)