This package can be utilized to make use of Jest as a testing framework for SharePoint framework solution.

It explains how test can be written for SPFx development.

It also provide shows how Entity merging using PnP Js can be implmented.

Usage : Step 1) Download the package 

            Step 2) Run the below commands in Windows powershell.

 

PowerShell
Edit|Remove
npm i
 
PowerShell
Edit|Remove
npm test
 

 

For more information on how Test driven development approach can be utilized in SharePoint Framework solution, refer the below article 

Introduction to Test driven development(TDD) of SharePoint Framework solution using Jest & Enzymes